Immunocytochemical analysis of oestrogen receptors and progesterone receptors in the human uterus throughout the menstrual cycle and after the menopause.

To obtain more insight into the relationship between cyclic and regional changes in steroid receptor expression and function-related changes in the various types of cell of the normal human uterus, we performed an immunocytochemical study on paraffin-embedded sections. The distribution and intensity of immunostaining for the oestrogen receptor and the progesterone receptor in the various types of cell were semiquantitatively scored. The data were statistically compared for the different phases of the menstrual cycle and after the menopause, and for the different regions of the corpus and (endo)cervix uteri. During the menstrual cycle, significant changes in oestrogen receptor score were observed in glandular and stromal cells of endometrium basalis and functionalis and in smooth muscle cells of the myometrium. In all types of cell, oestrogen receptor expression reached a maximum in the late proliferative phase. During the early secretory phase, oestrogen receptor staining declined sharply in stromal and smooth muscle cells, whereas, in glandular epithelium, oestrogen receptor expression decreased more gradually. During mid- and late-secretory phases, an increase in oestrogen receptor staining was also observed in predecidualizing stromal cells and smooth muscle cells. Progesterone receptor numbers changed significantly in glandular epithelium but not in stromal and smooth muscle cells. Glandular progesterone receptor expression reached a maximum in the early secretory phase and was then drastically reduced. During mid- and late-secretory phases stromal cells were moderately stained for progesterone receptor in contrast to epithelial gland cells which showed no or very weak staining. No regional variations in steroid receptor distribution in endometrium and myometrium were found.(ABSTRACT TRUNCATED AT 250 WORDS)     

Corrigendum to "The sow endometrium at different stages of the oestrous cycle: studies on the distribution of CD2, CD4, CD8 and MHC class II expressing" cells. [Anim. Reprod. Sci. 68 (2001) 99-109

The aim of this study was to investigate the distribution of CD2(+), CD4(+), CD8(+) lymphocyte subpopulations and MHC class II expressing cells in the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4 +/- 0.7 (mean +/- S.D.) were used. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus (day 17, n = 3), prooestrus (day 19, n = 3), oestrus (day 1, n = 3), early dioestrus (day 4, n = 3) and dioestrus (days 11-12, n = 3), were stored in a freezer at -70 degrees C until analysed by immunohistochemistry with an avidin-biotin peroxidase method using monoclonal antibodies to lymphocyte subpopulations and MHC class II molecules. The surface and glandular epithelium as well as connective tissue layers in subepithelial and glandular areas were examined by light microscopy. For the T lymphocyte subpopulations, all oestrous cycle stages and different tissue layers taken together, the most commonly observed cell type was CD2(+) cells. The largest number of CD2(+) cells within the surface and glandular epithelium were observed at oestrus and early dioestrus. In the surface epithelium, a larger number of CD8(+) cells compared with CD4(+) cells were observed and no CD4(+) cells were found within the glandular epithelium at any stage of the oestrous cycle. In the subepithelial and glandular connective tissue layers, during the oestrus cycle stages, a larger number of CD4(+) cells compared with CD8(+) cells were found. Endothelial cells in the connective tissue generally expressed MHC class II. However, no obvious differences between oestrous cycle stages were observed. For other cells than endothelial cells, the result was as follows. In the surface epithelium, a large number of MHC class II expressing cells was observed at oestrus compared with the other stages. No MHC class II expressing cells were found at late dioestrus and dioestrus. MHC class II expressing cells were also found in the glandular epithelium, and in the subepithelial and glandular connective tissue layers during all oestrous cycle stages but with no significant differences between stages. In conclusion, the present study showed a variation in the distribution of T lymphocyte subpopulations (CD2(+), CD4(+) and CD8(+)) and MHC class II expressing cells in the sow endometrium during different stages of the oestrous cycle. Also a variation between different tissue layers was found. It is suggested that helper and cytotoxic function of the immune system have primary locations in different tissue layers of the endometrium.     

Epidermal growth factor inhibits morphogenesis of the embryonic quail uropygial gland cultured in vitro

Formation of the uropygial papilla and glandular lumena was inhibited when the uropygial rudiment of a day 8 1/3 quail embryo was cultured for 2 days in a chemically defined medium in the presence of 50 ng/mL of epidermal growth factor (EGF). The epithelium of EGF-treated explants remained at the placode stage, or underwent minor invagination into the mesenchyme and became stratified like that of a 12- or 13-day-old embryo. EGF promoted cellular proliferation in the uropygial epithelium and the epidermis adjacent to the gland and it shortened the lag phase of proliferation and markedly stimulated epithelial DNA synthesis, detected immunocytochemically by labeling explants with 5-bromodeoxyuridine (BrdU). The maximal labeling index in EGF-treated uropygial epithelium was 55% higher than in the control. Electron microscopic observation revealed that the basal lamina had become irregular in the EGF-treated explants and that epithelial cytoplasmic processes penetrated through the basal lamina toward the mesenchyme. These same phenomena are observed in vivo when the glandular buds are formed during day 12–13. Some precocious changes occurred in the uropygial epithelium when the rudiment was cultured in the presence of EGF.     

Secretion mode of the harderian gland of rats after stimulation by cholinergic secretagogues.

We studied the morphological changes in rat Harderian glands 30 min after injection of cholinergic secretagogues. In controls, the glands exhibited a tubuloalveolar structure with relatively wide lumina, in which some osmiophilic dense droplets exocytosed from glandular cells were observed. Also two types of glandular cells (type A cells and type B cells sometimes showing exocytotic figures of lipid-secretory vacuoles) and myoepithelial cells were recognized. After injection of carbamylcholine chloride (subcutaneously, 0.1 mg/kg body weight), which has both nicotinic and muscarinic actions, many of the alveolar lumina dilated and contained a small number of osmiophilic droplets. Exocytotic figures in both types of cells and a pronounced decrease in the number of vacuoles in the glandular cells were observed. However, there was no evidence of apocrine or holocrine secretion. The injection of the higher dose of carbamylcholine (1.0 mg/kg) caused fusion of secretory vacuoles in the apical cytoplasm and contraction of myoepithelial cells. Most alveoli showed no clear lumina; their centers were jammed with cytoplasmic fragments and accumulated secretory products. Massive discharge of cytoplasmic fragments containing some secretory vacuoles was often observed. This may be classified as apocrine secretion. Bethanechol chloride (subcutaneous injection, 1.0 mg/kg), a muscarinic agonist, stimulated the Harderian-gland secretion, and enhanced exocytosis was observed. The discharge from the glandular cells, following injection of various doses of carbamylcholine, were almost inhibited by atropine sulfate, a muscarinic antagonist. The present results suggested that the cholinergic systems regulate the secretion of rat Harderian-gland cells which have muscarinic receptors.     

Differences in lectin binding patterns of normal human endometrium between proliferative and secretory phases

Lectin binding patterns in normal human endometrium were examined by light and electron microscopy using seven different lectins (ConA, WGA, RCA, PNA, UEA-1, DBA, and SBA). For light microscopic observations, criteria based on the incidence and intensity of cells positive for the lectin staining were adopted to evaluate the different staining patterns of the proliferative and secretory endometria obtained by the avidin-biotin-peroxidase complex (ABC) technique. At the light microscopic level, ConA, WGA, and RCA stained endometrial glandular cells in both phases. The number of PNA-positive cells with the binding sites entirely limited to the apical surface tended to be reduced slightly in the secretory phase. UEA-1 weakly stained the apical surface of glandular cells in the proliferative phase but not in the secretory phase. Among the lectins used in this study, DBA and SBA displayed remarkable changes between the phases. That is, in the proliferative phase they produced only a faint or slight positive stain at the apical surface, but the incidence and intensity of DBA- and the SBA-positive glandular cells increased in the secretory phase. By electron microscopy, the reaction product of ConA was observed in the plasma membrane, endoplasmic reticulum, nuclear envelope, and the Golgi apparatus, and the binding sites of RCA and DBA were observed in the plasma and Golgi membranes. Between both phases, the reactivity of ConA and RCA showed almost no change. However, the secretory endometrial cells containing the DBA-positive Golgi apparatus were markedly increased in number compared with the proliferative ones bearing the lectin-positive organelles.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ultrastructural changes in the oviductal epithelium of Merino ewes during the estrous cycle

Isthmic and ampullary oviductal epithelia sampled from Merino ewes at days -1, 1, 3, and 10 of the estrous cycle (estrus = day 0) were studied by scanning and transmission electron microscopy after fixation by vascular perfusion. Secretory cells, ciliated cells, and lymphocytelike basal cells were observed in both isthmic and ampullary epithelium at all stages of the estrous cycle studied and their ultrastructural features were analyzed. Synthesis of lamellated secretory granules occurred in the ampullary secretory cells during the follicular and early luteal phases, and their contents were released by exocytosis into the oviductal lumen during the luteal phase. Granule release was associated with nucleated apical protrusion of these cells into the oviductal lumen. No such secretory activity was displayed by isthmic secretory cells even though a few cells contained nonlamellated granules. Apocrine release of apical vesicles and accompanying cytoplasmic material from apical protrusions of ciliated cells occurred in the isthmus around estrus but not in the ampulla. This unexpected feature has not previously been reported in any other mammal. Dendritic basal cells were distinguished in the lower part of the epithelium by their heterochromatic nuclei, electron-lucent cytoplasm, and lack of attachment zones. No migration of basal cells was observed, and their ultrastructural features were similar in the ampulla and isthmus and at all stages of the estrous cycle examined. The function of these lymphocytelike cells in the epithelium is uncertain, but the presence of phagocytic bodies and lysosomes in 20% of them may indicate a phagocytic role.     

Endometrium--an extragonadal source of inhibin.

Using polyclonal antibodies generated against human seminal plasma inhibin (10.5 KDa), immunocytochemical localization was carried out in paraffin embedded tissue sections of human endometrial biopsies obtained at various phases of the menstrual cycle. A positive reaction which indicated the presence of inhibin was characterized by the presence of golden yellow or brown colour in the cytoplasm of epithelial cells that formed the glands as well as the luminal lining. The stromal cells however, showed negative staining. In early proliferative phase, the endometrial glands exhibited weak positive staining for inhibin which gradually increased and was intense in late follicular and early secretory phases. The intensity of the staining although was not diminished in the glandular epithelium in the mid as well as late secretory phases, the number of cells showing positive staining appeared to be reduced. Incubation of endometrial biopsies in vitro with labelled amino acid and immunoprecipitation of newly synthesized protein with specific antibodies to inhibin indicated that endometrium is capable of de novo synthesizing inhibin. The above results suggest that endometrium is an extra ovarian source of inhibin and the possible role of endometrial peptide in sperm fertilizing capabilities as well as in pre and post implantation events is suggested.     

Scanning electron microscopy of isolated epithelium of the murine gastrointestinal tract: morphology of the basal surface and evidence for paracrinelike cells

By using the method of Bjerknes and Cheng, isolated murine gastrointestinal epithelial sheets were prepared for scanning electron microscopy. Examination of isolated epithelium from fundic stomach revealed numerous branched gastric glands. Parietal cells were easily detected bulging from the basal surface of the glandular epithelium. The basal surface membrane of parietal cells appeared smooth, with only sparse microvilluslike projections, whereas adjacent glandular cells had numerous 1- to 2-micron fingerlike projections which interdigitated laterally with similar processes from adjacent cells. Occasionally, paracrinelike cells having long cytoplasmic processes ranging from 10 to 20 micron in length were observed on the basal epithelial surface of the stomach and the colon, but not the small intestine. In isolated intestinal epithelia, the basal surface of crypt epithelial cells showed extensive cytoplasmic interdigitations, but no distinct morphology permitting recognition of individual cell types. Various stages of intestinal crypt bifurcation were seen. Craterlike spaces in the basal surface of crypt epithelium, presumably due to migrating leukocytes, were also numerous. Examination of the luminal surface of the isolated intestinal epithelium revealed that intimate associations between epithelium and mucosal-associated microorganisms were maintained, thus suggesting that minimal alterations in surface morphology were incurred by epithelial isolation. These observations on epithelial structure suggest that isolated gastrointestinal epithelia may be well suited for physiological studies of epithelial function and interactions with the microbial flora.     

Immunohistological localization of human endometrial secretory protein, 'pregnancy-associated endometrial alpha 2-globulin' (alpha 2-PEG), during the menstrual cycle

The distribution of alpha 2-PEG, a human analogue of beta-lactoglobulin, in endometrium at different phases of the cycle was determined using immunohistochemistry with monoclonal and polyclonal antibodies. In the epithelial cells of glands in the functional zone of the endometrium, alpha 2-PEG was first detectable from Days 19 to 21 during the mid-luteal phase and maximal immunostaining was observed during the end of the late luteal phase. Intense staining in the glandular secretions and weaker staining in surface luminal epithelial cells during this period were observed. A minor population of basal glands contained alpha 2-PEG during the follicular phase. These results suggest that alpha 2-PEG synthesis by the glandular epithelium of the regenerated endometrium is hormonally regulated. Maximal staining occurring during the late luteal phase suggests that regulation may be related to the hormonal requirement for pre-decidualization rather than that required for histologically defined glandular epithelial secretion.     

Ultrastructure and ontogeny of the mandibular glands of the queen honey bee,Apis mellifera L. (Hymenoptera: Apidae)

Each mandibular gland of the queen bee, Apis mellifera L. (Hymenoptera: Apidae) consists of an axial cavity lined with a thin cuticular intima, secreted by a flat epithelium, and numerous glandular units (type 3), each unit with one duct cell and a large polyploid glandular cell. Mitochondria and endoplasmic reticulum are preponderant organelles. During the ontogeny of the queen bee, the ultrastructure of the glandular cells evolves as her level of pheromonal activity. Variations mainly concern the mitochondrial system. Hence, at the beginning of the imaginal life, the homogeneous population of small mitochondria increases. Towards the 3rd–5th day of the queen's imaginal life, the pheromonal activity increases and the mitochondrial differentiation results in the appearance of giant forms. During the highest activity phase (6 to 18-month-old queens), giant mitochondria, associated with endoplasmic reticulum, invade cytoplasmic areas. In queens aged from 18 to 24 months, the reduction of pheromonal and secretory activities is associated with the reduction of mitochondrial population as well as with the accumulation of lipid droplets and various lytic structures.     

Morphological characterization of actively fusing L6 myoblasts

We have characterized morphologically the surface of L6 myoblasts at the time of active cell fusion using transmission electron microscopy. Two subclones of the L6 line were used in these studies: the L6Cl55 line that fuses to form multinucleated syncytia and the NF44 non-fusing variant. Ultrastructural analysis revealed an electron-opaque material at localized points of cell-cell apposition in actively fusing L6Cl55 cells. This material may be transported by and secreted from smooth-surfaced cytoplasmic vesicles with an electron-dense core. In contrast to L6Cl55 cells, the electron-dense plaques were seen infrequently in cultures of the NF44 non-fusing variant. This previously unidentified substance may be associated with cell-cell recognition or adhesion, both necessary prerequisites for myoblast membrane fusion. Alternatively, the electron-dense plaques may be directly involved in the fusion event.     

Cytodifferentiation in the accessory glands of Tenebrio molitor. X. Ultrastructure of the tubular gland in the male pupa

The tubular accessory gland consists of a simple secretory epithelium surrounded by a muscular coat. Over the pupal instar, the gland increases ten-fold in volume and 15-fold in length. Pupal development is divisible into a phase of mitosis and one of cell growth. During the mitotic phase, cytoplasmic membranes are sparse and nuclei move toward the luminal face of the epithelium to undergo division. In the cell growth phase, the cells become more columnar, a few stacks of rough endoplasmic reticulum are formed, and small dense secretory vesicles appear near the apical surface. The hormonal control of the developmental sequence is discussed.     

The sow endometrium at different stages of the oestrous cycle: studies on the distribution of CD2, CD4, CD8 and MHC class II expressing cells

The aim of this study was to investigate the distribution of CD2+, CD4+, CD8+ lymphocyte subpopulations and MHC class II expressing cells in the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4+/-0.7 (mean+/-S.D.) were used. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus (day 17, n=3), prooestrus (day 19, n=3), oestrus (day 1, n=3), early dioestrus (day 4, n=3) and dioestrus (days 11-12, n=3), were stored in a freezer at -70 degrees C until analysed by immunohistochemistry with an avidin-biotin peroxidase method using monoclonal antibodies to lymphocyte subpopulations and MHC class II molecules. The surface and glandular epithelium as well as connective tissue layers in subepithelial and glandular areas were examined by light microscopy.For the T lymphocyte subpopulations, all oestrous cycle stages and different tissue layers taken together, the most commonly observed cell type was CD2+ cells. The largest number of CD2+ cells within the surface and glandular epithelium were observed at oestrus and early dioestrus. In the surface epithelium, a larger number of CD8+ cells compared with CD4+ cells were observed and no CD4+ cells were found within the glandular epithelium at any stage of the oestrous cycle.In the subepithelial and glandular connective tissue layers, during the oestrus cycle stages, a larger number of CD4+ cells compared with CD8+ cells were found.Endothelial cells in the connective tissue generally expressed MHC class II. However, no obvious differences between oestrous cycle stages were observed. For other cells than endothelial cells, the result was as follows. In the surface epithelium, a large number of MHC class II expressing cells was observed at oestrus compared with the other stages. No MHC class II expressing cells were found at late dioestrus and dioestrus. MHC class II expressing cells were also found in the glandular epithelium, and in the subepithelial and glandular connective tissue layers during all oestrous cycle stages but with no significant differences between stages.In conclusion, the present study showed a variation in the distribution of T lymphocyte subpopulations (CD2+, CD4+ and CD8+) and MHC class II expressing cells in the sow endometrium during different stages of the oestrous cycle. Also a variation between different tissue layers was found. It is suggested that helper and cytotoxic function of the immune system have primary locations in different tissue layers of the endometrium.     

THE DEVELOPMENT OF SURFACE SPECIALIZATION IN THE SECRETORY EPITHELIUM OF THE AVIAN SALT GLAND IN RESPONSE TO OSMOTIC STRESS

Cell surface specialization, a characteristic common to most ion-transporting epithelia, was studied in the salt (nasal) gland of the domestic duck in relation to osmotic stress. Three days after hatching, experimental ducklings were given 1% NaCl to drink for 12 hr and freshwater for the remainder of each day. Control ducklings were maintained exclusively on freshwater. The fine structure of the secretory epithelium was examined on various days of the regimen. The nasal gland epithelium of the secretory lobule is composed of several types of cells. Peripheral cells, lying at the blind ends of the branched secretory tubules, are similar in both control and experimental animals at all stages of glandular development. These generative cells contain few mitochondria and have nearly smooth cell surfaces. Partially specialized secretory cells predominate in the secretory tubules of control animals and appear as transitional cells in the tubular epithelium of salt-stressed animals. These cells contain few mitochondria and bear short folds along their lateral cell surfaces. Fully specialized cells dominate the secretory epithelium of osmotically stressed ducklings. The lateral and basal surfaces of these cells are deeply folded, forming complex intra- and extracellular compartments. This vast increase in absorptive surface area is paralleled by an increase in the number of mitochondria that pack the basal compartments. The development of this fully specialized cell is correlated with the marked increase in (Na⁺-K⁺)-ATPase activity in the glands of osmotically stressed birds.     

Ultrastructure and innervation of water buffalo (Bubalus bubalis) seminal vesicle.

The lining epithelium of secretory end pieces and central glandular duct in the seminal vesicle of the water buffalo (Bubalus bubalis) consists of columnar principal and small polymorphous basal cells. A system of intercellular and even intracellular canaliculi enlarges the secretory surface. The most prominent organelle of the columnar principal cells is the granular endoplasmic reticulum, forming large aggregates of parallel lamellae. Using antibodies against the neural cell adhesion molecule L1 and the neural marker protein gene product 9.5 (PGP 9.5), the innervation pattern of the seminal vesicle becomes evident. The muscular layer surrounding the propria contains a dense network of unmyelinated fibers. Thicker bundles traverse the muscular layer to reach the propria. Around glandular secretory tubules and below the epithelial lining of the glandular duct a tightly woven subepithelial plexus is observed which sends short penetrating branches into the basal zone of the epithelium. These intraepithelial nerves are devoid of Schwann cells and basal lamina (naked axons) and are situated within the intercellular spaces between principal and basal cells. Acetylcholinesterase histochemistry with short (1-2 h) incubation times, dopamine-beta-hydroxylase immunohistochemistry and ultrastructural study of transmitter-containing vesicles was performed. The results suggest that muscular contraction in the seminal vesicle is predominantly under the influence of the sympathetic nervous system, whereas secretory epithelial function is regulated by both sympathetic and parasympathetic fibers.     

Enzyme Histochemistry as a Link between Biochemistry and Morphology

A study has been made of the progress of involution of the mouse and rat mammary gland using histologic, electron microscopic, histochemical and autoradiographic methods. Particular emphasis has been placed on the morphology, metabolic alte-rations and activities of histochemically identifiable enzymes, and on the pharmacologic effects of lactation inhibiting agents and cytostatic drugs on lactation and involution. In order to allow a systematic investi-gation, involution was initiated in rats and mice by ligation of individual gland ducts at various time intervals. Both lactating glands and glands in different phases of involution were thus available in a given animal.The most important observation was that involution, which altogether takes approximately 2 weeks to be complete, involves a three-phase process, each phase being clearly distinguishable by morphologic and histochemical criteria. The first phase comprises approximately 4 days during which production of milk may be reinitiated. The second phase starts on day 5 of involution and constitutes the period of involution per se characterized by appreciable parenchymal cell degradation. The third phase, which starts around day 10, is the period of reorganization to the resting mammary gland.Early in the first phase of involution, substantial alveolar enlargement due to engorgement with milk, together with epithelial flattening, are prominent features. By day 3, the glandular contents decrease again in volume, the number of glandular cells and the constituent cytoplasmic organelles remaining unchanged during this period, except for the diminished appearance of fat droplets. In addition to normal appearing vacuoles with only occasional or sparse protein granules, giant vacuoles containing, in part, several hundred casein granules are found. Their formation appears to be due to increased stacking of granules in distended vacuoles prior to dissociation from the Golgi apparatus. In addition, however, the enhanced reactions of a1P (alkaline phosphatase) and ATPase, which are found in the apical plasmalemma, are suggestive of resorptive activities. Protein particles absorbed from the glandular lumen equally appear to have a capacity for fusing into large vacuoles. The large protein granule-containing vacuoles regularly exhibit intense (3-Glu activity. This enzyme would appear to contribute actively to the degradation of excess milk during the first phase of involution.Autoradiographic studies reveal that the synthesis and release of proteins into the secretion is maintained for 3 days. While 3H-tyrosine uptake by the alveolar cells continues unchanged, the incorporation of 3H-palmitic acid into glandular lipoids, and of 3H-fucose into glandular polysaccharides is virtually blocked completely. An immediate reaction of the lipoid metabolism is also indicated by the decrease in 3HBDH activity on the first day of involution.The activities of the histochemically detected oxidoreductases (LDH, MDH, SDH, G6PDH, 3HBDH) show a sharp fall on day 1 of involution, reaching levels approximately one half of the activity observed during lactation, as shown on micro densitometry. The activities remain unchanged during the following 4 days.No degradation of glandular parenchyma is noted during the-first phase of involution. The glandular cells rather take a -wait-and-see- attitude which enables them to participate again in the secretion of milk, as need arises. At this time the activities of the enzymes implicated in energy metabolism have reached approximately the resting mammary gland level. Only protein synthesis is maintained virtually unrestricted and this results in the production of excess milk constituents that are degraded as soon as they are being formed.In the second phase of involution, large seg-ments of the glandular epithelium undergo invo-lution, a process which involves the destruction of glandular epithelial cells and the removal of the resulting cellular debris from the mammary gland. The glandular cells remaining are transformed into resting cells. The lysosomes of the glandular epithelial cells, with maximum numbers being attained between days 7 to 9, contribute decisively to this degradative process. Ultra-structurally, this stage is initially characterized by the appearance in the alveolar cell cytoplasm of segregated cytoplasmic areas which stain negatively for acP (acid phosphatase) and are rich in organelles. These cytoplasmic areas change to membrane-bordered lysosomes which possess intense acP activity. The lysosomes are obviously required for the autophagic degradation of cytoplasmic segments. At the same time the activities of other lysosomal enzymes, involving acP, N-A-Gase, AMPase and AS, show a sharp increase. ATPase and TPPase likewise exhibit considerably increased activity during the second phase of involution. It is seen on microdensitometry that during this phase the acP attains approximately three times the lactation activity. In contrast, the activity of (3-Glu, after having shown a very high increase during the first phase, reverts again to the resting mammary gland level.During the second phase of involution, the oxidoreductases are subject to a further drastic decline of their activities. This process, which consistently affects all segments of the mammary gland,,comes to completion within a few hours. The reaction is found to be minimal around day 5 of involution, at a time when the enzyme activities are approximately one quarter of the lactation levels.At this time, many alveolar cells are destroyed and released into the glandular lumen, the acP retaining its activity in the lysosomes of sloughed cells or cell debris. The resulting gaps in the alveolar epithelium are either bridged immediately or remain detectable on histology. Yet the glandular contents do not pass into the interstitial tissue. The adherence of the glandular tree and the glandular epithelium is ensured by myoepithelial cells. The basement membrane effects the complete segregation of the parenchyma from the interstitial tissue:Macrophages which at this stage occur increa-singly near the alveoli, in the alveolar epithelium and in regional lymph nodes, and which are conspicuous due to numerous acP-laden lysosomes participate essentially in glandular regression.The third phase of involution, which takes place approximately 10 to 14 days following the onset of milk stasis, is the period of reorganization to the resting mammary gland, a period during which glandular cells containing little cytoplasm and sparse organelle lining make their appearance. However, the activities of acP and other lysosomal enzymes remain elevated compared to the pregestational level. Histochemically, the reaction of the oxidoreductases is more intense than during the second involutionary phase, corresponding roughly to the level of the mammary gland in the resting state. The formation of the glandular epithelial cells of the resting mammary gland is not due to renewed mitotic activity, but results from the reduction of actively secreting epithelial cells.Throughout the period of involution the myo-epithelium consistently changes its shape. How-ever, cytoplasmic alterations are not discernible on electron microscopy, nor do these cells undergo degradation during glandular involution. The alP reaction is of particular value for the identification of the myoepithelial cells. No alteration in enzyme activities is demonstrable at the histochemical level throughout the process of involution.Alterations in the interstitial tissue affect particularly the adipose tissue. During lactation, the interalveolar space exhibits only a narrow connective tissue layer which changes insignificantly during the first phase of involution, whereas the subsequent incorporation of lipids results in the formation of plurilocular lipid cells and the reappearance of unilocular adipose tissue as involution advances. During this period the vessels move away from the alveoli.The response of the mammary gland to lactation inhibiting and cytostatic drugs varies, depending on the agent administered. Estrogencontaining drugs lead to an involutionary process which in its initial phase differs from that observed during normal glandular regression. Due to the fact that the milk continues to be suckled by the young, milk production however ceasing very rapidly, the (3-Glu activity is not found to increase greatly during the first phase of involution. The behavior of the lysosomal enzymes during the second phase resembles that seen during normal involution.After administration of the ergot alkaloid 2-Br-a-ergokryptine methane sulfonate (CB 154), the process of involution is initiated only in individual mammary gland cells if the young are left with the mother. In these areas involution takes a normal course. Altogether, milk production changes only insignificantly.The cytostatic drug 5-fluorouracil does not induce direct involution. Milk production apparently is not arrested. However, the pups, when left with the mother, die after 5 to 6 days. Death would appear to be due to the cytotoxic action of 5-fluorouracil.     

The architecture of the accessory reproductive glands of the male desert locust. 5: ultrastructure during maturation

The accessory reproductive glands of the male desert locust were studied with the electron microscope from the time of adult emergence until full sexual maturity was attained (10 days). Observations on the changes in the nucleus and the cytoplasm of the glandular epithelium, particularly those organelles involved in the elaboration of cell secretions, were made during the maturation of the accessory glands. Cells of gland 16 (the functional seminal vesicle) exhibit numerous ribosomal aggregates, have a concentration of mitochondria along their luminal surface, and show some secretory activity, even at the time of adult emergence. On the other hand, all other accessory glands show very little development of the secretory apparatus (rough-surfaced endoplasmic reticulum, polyribosomes, Golgi elements, elaborate mitochondria, etc.) until after the fifth adult day. These changes parallel changes in the secretory activity of the adult corpus allatum; and it is suggested that the corpus allatum hormone regulates the maturation of the truly glandular accessory glands of the locust, but not that of the functional vesicle.     

Functional morphology of the midgut of Aedes aegypti L. (Insecta,Diptera) during blood digestion

Morphometric analysis of the epithelial lining of the stomach of A. aegypti suggests that digestion of the first blood meal in the stomach of this species can be viewed as a series of phases that can be correlated with physiological data from the literature. In phase Ia (0-10 h after blood meal [abm]) the whorls of the rough endoplasmic reticulum unfold, the Golgi zones increase, and the basal labyrinth is enlarged. This coincides with processes of synthesis and secretion (e.g., peritrophic membrane, esterases and lipases) and transport by the stomach epithelium. In phase Ib (10-20 habm) the cellular parameters measured further increase, indicating high synthetic and secretory activities (e.g., digestive enzymes). In phase Ic (20-30 habm) cell structures involved in synthesis and secretion still exhibit high values coinciding with maximal activity of proteases in the gut. Enhanced surface area of microvilli, prominent lipid inclusions, and appearance of glycogen deposits in the gut epithelium suggest increased absorption, storage, and transport functions of the stomach cells. In phase II (30-36 habm) structural alteration points to a gradual shift from synthesis and secretion to absorption, partial storage, and transport of nutrients. In phase III (36-72 habm) the cellular apparatus is reduced concomitant with the ending of the digestive cycle. Lipid inclusions and glycogen deposits disappear from the stomach epithelium.     

Ultrastructural study of the ventral lobe of the prostate of mice with streptozotocin induced diabetes (C57BL/6J)

Morphological and functional changes caused by diabetes in the accessory sex organs and especially the prostate have been reported by several investigators. The aim of the present study was to examine the possible deleterious effects of experimentally induced diabetes on the secretory epithelium of the ventral prostate of mice. Sixteen adult male C57BL/6J mice were divided into two groups. The diabetic group received a streptozotocin injection of 75 mg/kg, while the control group received only 0.1 ml citrate buffer, i.p. After 30 days, the diabetic state was ascertained, the animals were sacrificed and the ventral lobe of the prostate was collected for histological and ultrastructural examination. The results showed reduction in glandular epithelium cell height, increased numbers of cytoplasmic vacuoles and thickening of the extracellular matrix. In conclusion, experimental diabetes has harmful effects on the secretory epithelial cells of the ventral lobe of the prostate of mice.     

Ultrastructural changes in guinea pig endometrial cells during the estrous cycle.

In the guinea pig, the estrous cycle is characterized by a constant measurable level of plasma progesterone with two peaks: the first one associated with the peak of plasma estradiol-17 beta occurring at proestrus and the second, during diestrus, more pronounced at the time at which the level of estradiol-17 beta is undetectable. The progesterone receptor content is the highest on day 1 and the lowest on day 10 of the estrous cycle, which lasts 16.3 +/- 1.5 days (n = 37; mean +/- SD). There is a positive correlation between the plasma level of estradiol-17 beta and the progesterone receptors detected immunocytochemically in both endometrial epithelial and stromal cells. The general morphology of the endometrium during proestrus and estrus is consistent with an estrogenic stimulation, i.e., a smooth and regular surface of the endometrium and the presence of numerous microvilli on the cell surface. However, a moderate secretory activity also occurs in proestrus and estrus. During postestrus, the glandular cells display an increase in characteristic secretory features which parallels the rise of progesterone in the plasma.