The fine structure of the lutein cells in the mink (Mustela vison) with special reference to the secretory activity during pregnancy

Summary The ultrastructure of the lutein cells in the mink throughout pregnancy and the regression periodpost partum is described. To correlate the fine structure with the changes in the peripheral plasma progesterone levels, the concentrations of progesterone were measured by a rapid competitive protein-binding assay.Even during the delay period (e.g. as long the plasma progesterone levels remain at the basal level, <8ng/ml), the lutein cells in the mink exhibit structural criteria of functional activity. However, the increase in progesterone secretion is accompanied by some morphological transformations, characterized by the presence of more and more small dense homogenous bodies in the cytoplasm, which become irregular and scalloped during the stage with maximum release of progesterone. At this stage the agranular endoplasmic reticulum is often cisternal or vesicular.During the decline of the progesterone levels, typical and moderate electron-dense lipid droplets are found increasingly more within the lutein cells. The expanded agranular ER is now more sparse, while the granular ER becomes more pronounced, often forming parallel arrays. During this phase the mitochondria become elongated, dumb-bell, or cup shaped. After parturition the corpora lutea consist of cells in various stages of degeneration. At day 14post partum only a few lutein cells are still identifiable.Evidently the observed morphological changes take place in the lutein cells during the life span of corpora lutea. This feature lends further support to the concept that the mink lutein cells are steroid-producing cells and furthermore, that the corpora lutea may be the main sites of gestagen production during pregnancy.     

Ultrastructural analysis of the granulosa — Luteal cell transition in the ovary of the dog

The transition from ovarian granulosa to lutein cell during the estrus cycle of 60 pregnant and non-pregnant beagle bitches was analyzed by light and electron microscopy (both 100 and 1000 KV). Early proestrus was characterized by a gradual rise in serum estrogen levels, hyperplasia of the granulosa cells, the accumulation of follicular fluid, and the development of tortuous intercellular channels. During the second half of proestrus, serum estrogen levels continued to rise, but growth, division, and differentiation of the granulosa cells was minimal. Estrus was marked by the first acceptance of the male and a well-defined LH peak In the subsequent 24 hour period, the granulosa-lutein cells hypertrophy rapidly and develop a large Golgi apparatus, small profiles of granular endoplasmic reticulum, numerous microfilaments, and large gap junctions between the cells. Mitochondria also proliferate, enlarge, and elongate, but retain lamelliform cristae. Luteinization of the cells and progesterone secretion begin just after ovulation which in turn occurs about 24 hours after the LH peak. On the third and fourth day of estrus, numerous small vesicles of agranular endoplasmic reticulum fill the extoplasm and the mitochondria swell up and round off. The vesicles rapidly fuse into whorled and flattened cisternae or anastomosing tubules of agranular endoplasmic reticulum, while the mitochondria develop tubulovesicular cristae. These structures gradually become organized with respect to the basal lamina. The Golgi apparatus is centered over the pole of the nucleus that faces the pericapillary space. Stacked and whorled cisternae of agranular ER develop in the lateral margins and avascular end of the cell while mitochondria and tubular elements of agranular ER predominate in the central medial and most basal portions of the cytoplasm. Microfilaments are ubiquitous and appear to be instrumental in this orientation process. The cell surface develops three distinct regional specializations that coincide with the underlying cellular compartments: interconnecting pleomorphic folds fill the pericapillary space; long tenous microvilli project from the lateral cell surface and form tortuous intercellular channels and canaliculi; and large gap junctions form along the margins of the cell furthest removed from the basal lamina. By the sixth day of estrus, the granulosa-luteal cell transition is nearly complete and serum progesterone levels are on the rise.     

Fine structure of the corpus Luteum of the raccoon during pregnancy

Summary Ultrastructure of the granulosa lutein cells of the raccoon from throughout pregnancy has been described. The lutein cells often from epithelial cords which are separated by the connective tissues, capillaries and lymphatics. Based on the arrangements and modifications of the cytoplasmic organelles and inclusions, three types of lutein cells have been recognized. The type I lutein cells predominantly contain tubular, agranular endoplasmic reticulum, juxtanuclear Golgi complexes, a few round to rod-shaped mitochondria, some free ribosomes, and occasional lipid droplets. Occasionally the tubular cristae of mitochondria and tubular smooth endoplasmic reticulum appear contiguous. The type II cells contain abundant lace-like and/or stacked fenestrated endoplasmic reticulum cisternae that frequently form membranous whorls, some tubular, agranular endoplasmic reticulum, mitochondria, and lipid droplets. Mitochondria are usually small, but unusual large ones also occur. The small, rod-to round-shaped mitochondria usually have tubular cristae; but the large, oval, elongate, and cup shaped mitochondria possess tubular, lamellar, plate like, and whorl-like cristae. The plasma membranes of the cells are complexly elaborated and folded, especially when apposing each other. In favorable sections, strands of fenestrated cisternae appose the folds of the plasma membranes. In general, the amount of cytoplasmic organelles and inclusions vary greatly in the cells. The type III cells predominantly contain lipid droplets and sparse cytoplasmic organelles. The type I and II cells are found throughout pregnancy, but the type III cells are observed from mid gestation to term. The cytological features of type I and II cells suggest that they probably secrete most of the steroids, whereas the type III cells primarily store lipids.This research was supported by UPSHS grant AM-11376 and NIH contract 69-2136.     

Feinstruktur der Luteinzellen des Meerschweincheneierstocks während der Schwangerschaft und des Zyklus

Zusammenfassung Die Feinstructur der Luteinzellen des Meerschweinchens während Schwangerschaft (15., 35., 45., 50., 55., 63. und 2 Tage nach der Geburt) und Zyklus (9, 14, 16, 20 Tage nach der Ovulation) wurden elektronenmikroskopisch untersucht. In den aktiven Luteinzellen kann man konzentrisch um die Lipoidtropfen angeordnete Strukturen des agranulären endoplasmatischen Retikulum beobachten, die später durch Membranstrukturen des granulären endoplasmatischen Retikulum ersetzt werden. Die Mitochondrien sind rund und enthalten tubuläre Innenstrukturen, die Lipoidtropfen sind elektronenoptisch dicht. Während der Rückbildung des Corpus luteum setzt sich das endoplasmatische Retikulum aus ungeordneten Vesikeln und Tubuli zusammen, die Mitochondrien sind länglich oder verzweigt, die Lipoidtropfen elektronenoptisch hell. Die Bedeutung dieser feinstrukturellen Veränderungen in der Luteinzelle wird diskutiert.

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The ultrastructure of lutein cells in the guinea pig corpus luteum during pregnancy and oestrous cycle

Summary The fine structure of the lutein cells in guinea pigs corpora lutea of pregnancy (15th, 35th, 45th, 50th, 55th, 63th day and 2 days after birth) and during oestrous cycle (9, 14, 16, 20 days after ovulation) is described. During the active phase of the corpus luteum the formation of concentric whorls of agranular endoplasmic reticulum around lipid droplets is observed, but later the granular endoplasmic reticulum increases. In this stadium the mitochondria are round with tubulous cristae and the lipid droplets are increased in density. During the involution of the corpus luteum the endoplasmic reticulum does not form concentric whorls, the mitochondria are elongated, polymorphic, the lipid droplets have lower electron density. These ultrastructural changes in the lutein cells are discussed concerning the role of the cell organelles in the steroid synthesis.

Diese Arbeit wurde mit Unterstützung durch die Alexander von Humboldt Stiftung durchgeführt.     

OSMIUM STAINING OF ENDOPLASMIC RETICULUM AND MITOCHONDRIA IN THE RAT ADRENAL CORTEX

The zona fasciculata of the rat adrenal cortex synthesizes and secretes glucocorticoids. As observed after aldehyde fixation, the cells in this zone contain an extensive endoplasmic reticulum (ER), a small Golgi apparatus, a moderate number of lipid droplets, and abundant mitochondria with tubulovesicular cristae. Numerous areas within the endoplasmic reticulum and mitochondrial cristae appear clear. In addition, a small percentage of mitochondria encompasses large, clear areas. After immersion of finely minced adrenal cortex in unbuffered 2% OsO₄ (40–48 hr at 40°C), deposits of osmium are seen within the Golgi apparatus, the entirety of the ER, and occasionally within mitochondria. In some mitochondria, the deposits are within cristae; in others, within vacuoles; in still others, in both cristae and vacuoles. These localizations correspond best to the clear areas found in aldehyde-fixed tissue. Osmium is not deposited in lipid droplets, in bar-containing inclusions, in mitochondrial matrix inclusions, or in the peripheral, outer mitochondrial spaces. Addition of zinc-iodide to OsO₄ increases the amount of Golgi apparatus and mitochondrial staining. Adrenocorticotropin (ACTH) does not affect the localization of deposits; hypophysectomy decreases mitochondrial staining. This study (a) emphasizes the necessity for electron microscopic confirmation of osmium localization when this technique is used as a Golgi apparatus stain; and (b) suggests that the ER-staining pattern may be consistent in cells actively synthesizing steroids or steroid-like compounds.     

Ultrastructure of meristematic epidermal cells of maize root under water deficit conditions

Summary Structural components of meristematicZea mays primary root epidermal cells were observed after osmotic stress of the nutrient medium (12.5 atm.) and after rehydration. After non-lethal osmotic stress (24 hours), aggregation of nuclear chromatin, parallel ER arrangement, and reduction of mitochondrial cristae were found. Increased number of Golgi cisternae indicated vesicle production inhibition, and microtubules were absent in treated cells, although plastid structure remained unchanged. After lethal osmotic stress (48 hours), fragmentation of cytoplasmic membranes and a more severe structure damage of all cellular components occurred. Structure of the nucleus, mitochondria, Golgi apparatus and microtubules reappeared in the cells after rehydration. The only new feature of these cells was occurrence of smooth ER, which may indicate that the ER system has acquired a different function in regenerated cells.     

Ultrastructural changes in corpora allata during a cycle of juvenile hormone biosynthesis in embryos of the viviparous cockroach, Diploptera punctata

We have observed changes with time in the fine structure of corpora allata (CA) during a known cycle of increasing and decreasing juvenile hormone (JH) synthesis in late embryos of Diploptera punctata. A previous report showed that rates of JH release were relatively low in 28-day-old embryos, but CA activity subsequently rose linearly to a peak on about day 42, and thereafter steadily declined to a low level on day 64 just before birth (Holbrook et al., 1997). We now show that, regardless of rate of JH synthesis, CA cells are large and replete with organelles which nevertheless exhibit variable morphology in embryos of different age. Highly active CA cells on day 40 contain abundant ring-form mitochondria, whereas CA cells of low activity on days 28 and 64 contain mitochondria that are rod-shaped or globular. Mitochondrial cristae were scarce and indistinct on day 28 but numerous and well developed on day 64. Endoplasmic reticula (ER) are rare on day 28 and appear in increasing numbers when CA activity rises. On day 40, ER are abundant and often exhibit a whorl-like appearance which is not observed on day 28. After day 44, when biosynthetic activity is declining, whorls of ER gradually decrease in number and are ultimately replaced by vesicular smooth ER on day 64. Neurosecretions are found only after day 38, by which time rates of JH synthesis have increased substantially from those of day 28. Except for membranous autophagic vacuoles, which are frequently found when ER whorls disintegrate as rates of JH synthesis decline toward birth, most autophagic vesicles such as multivesicular vesicles and dense bodies occur only sporadically among CA cells at all examined ages. We conclude that synchronous autophagy of exhausted organelles, which results in atrophy of CA cells and long-term arrest of JH synthesis in adult females of D. punctata, does not occur in embryos. The slow cyclic change in rate of JH synthesis in embryonic CA is most likely due to asynchronous autophagic activity and to alterations in certain unique features of intracellular organelles.     

Ultrastructural changes in granulosa lutein cells and progesterone levels during preimplantation,implantation, and early placentation in the western spotted skunk

Summary The ultrastructure of corpora lutea obtained during the preimplantation, implantation and early postimplantation periods has been studied in 20 western spotted skunks. Fine structure of granulosa lutein cells was correlated with progesterone levels. The corpus luteum of the prolonged (7 month) preimplantation period contained undifferentiated small granulosa cells and differentiated large granulosa lutein cells. The former ranged in size between 12 and 20 and the latter between 20 and 45 . The ratio of small and large cells was about equal in an animal 2 days prior to nidation whereas only few small cells and numerous large cells were observed in an animal estimated to be 8 to 12 hours from nidation. Occasionally small cells were observed amidst large ones during the 24 hour nidation period, i.e. adhesion of trophoblast with the luminal uterine epithelium, but small cells were absent in animals after this period. Small cells had some smooth and rough endoplasmic reticulum, rod-shaped mitochondria with platelike cristae, small Golgi complex, and relatively smooth plasma membranes. Large lutein cells had abundant smooth endoplasmic reticulum, membranous whorls of smooth endoplasmic reticulum, usually round mitochondria with tubular and lamellar cristae, a well developed Golgi complex, variable amounts of lipid droplets, and highly plicated and ruffled plasma membranes. Peripheral plasma progesterone levels during the prolonged preimplantation period ranged between 1.1 and 7.9 ng/ml, but during implantation it was between 8 and 16.6 ng/ml. It is suggested that plasma progesterone levels fluctuate during the time of implantation and should not be regarded as a basis to predict actual nidation in the western spotted skunk.This research was supported in part by Grant Number HD06556 from the National Institute of Child Health and Human Development.     

The mitochondrial complex in cryptophyceae

The unitary nature of the mitochondrion and the characteristic flattened finger-like morphology of the cristae were demonstrated in the Cryptophyceae. Hemiselmis rufescens contained an unbranched vermi-form mitochondrion in contrast to the variously branched complex, comprising an interconnected peripheral and central reticulum, in Chroomonas sp. and strains of Cryptomonas. The systematic value of the shape and distribution of the mitochondria in the examined genera was suggested.     

Distribution and Structure of the Adrenocortical Homolog in Polypterus palmas Ayres

The identity, distribution and structure of the adrenocortical homolog (AH) was made in Polypterus palmas Ayres using routine light and electron microscopy and histochemistry for the enzyme δ⁵-3β-hydroxysteroid dehydrogenase (3β-HSD). The AH is confined to yellow corpuscles which are positioned near the posterior cardinal and renal veins in the anterior two-thirds of each kidney. The 46–57 spherial to cigar-shaped corpuscles are placed end to end and are equally distributed in the kidneys. The tortuous cords of epithelial cells of each corpuscle are surrounded by sinusoids and are completely delimited from the haemopoietic and renal tissue of the kidneys. The steroidogenic nature of the cells is demonstrated by their 3β-HSD activity and their ultrastructure, namely lipid droplets, tubular smooth endoplasmic reticulum and mitochondria with tubulovesicular cristae. Giant mitochondria and gap junctions are notable features of AH cells in this fish. The yellow corpuscles of the kidneys in P. palmas represent the AH and this tissue has a distribution which is in accordance with the taxonomic position of Polypteriformes.     

The reversibility of the ethidium bromide-induced alterations of mitochondrial structure and function in the cellular slime mold,Dictyostelium discoideum

Addition of ethidium bromide to ameboid cultures of the slime mold,Dictyostelium discoideum, caused a cessation of cell division after 1 or 2 generations. The replication of mitochondrial DNA was immediately blocked as indicated by the 50% decrease in the DNA content of purified mitochondria from ethidium-bromide-treated cultures. The activity of the respiratory chain was also inhibited, resulting in a 75% decrease in cyanide-sensitive whole cell respiration. Spectral analysis at low temperature indicated that the amount of cytochromec ₁ was decreased 80% and that of cytochromec increased 100% in mitochondria from treated cells. Two cytochromesb absorbing at 556 and 561 nm were observed in mitochondria from both control and ethidium-bromide-treated cultures. The content of cytochromeb ₅₆₁ appeared to decline more than didb ₅₅₆, but it is hard to quantitate the decrease. The effects of ethidium bromide were fully reversible. When the drug was removed, the cells resumed a normal growth rate without any discernible lag. The activity of oligomycin-sensitive ATPase, cytochrome oxidase, and succinate-cytochrome-c reductase as well as the cytochrome content began to increase after 1 day returning to control levels within 5 days. Electron micrographs of whole cells treated with ethidium bromide revealed that mitochondrial profiles were elongated and had greatly reduced cristae. Numerous membrane whorls were apparent, as was a profound loss of rough endoplasmic reticulum. Three days after removal of ethidium bromide, mitochondria were again ovoid in shape and contained well-developed cristae. In all of the cells during recovery, there was a single large vacuole that appeared to enclose a large portion of the cell volume, forming a new cellular compartment that may simplify the breakdown of previously damaged organelles.This work is in partial fulfillment of the requirements for the Doctor of Philosophy degree at the City University of New York.     

Studies of the functional activity of mitochondria and cell ultrastructure of the coleoptile in wheat,Agropyron and their hybrids (incomplete amphidiploids) during decreasing temperature

Summary The structure of the mitochondria and endoplasmic reticulum in the coleoptile of plants (Triticum aestivum var. Lutescens 329, Agropyron glaucum, Triticum × Agropyron 56-chromosome hybrids, incomplete amphidiploids, TAH, containing 42 wheat chromosomes and 14 chromosomes of genomes D or X of Agropyron), which differ in winterhardiness, was studied after exposure to 0 ° and -4 °C for periods varying from 10 min to 4 days. The functional activity of mitochondria isolated from 3 day old seedlings was also investigated in these cereals. The cells of Triticum and Agropyron seedlings grown at 23 °C were shown to differ in mitochondrial structure. In the cells of TAH both kinds of mitochondria were found.On day 4 of exposure to -4 °C, the mitochondria of Agropyron cells were not changed; the endoplasmic reticulum formed complex closed cavities. Under similar conditions most wheat mitochondria were destroyed and in the rest no cristae were observed.Morphometric analysis indicated that the volume of such mitochondria increases by two times, while the surface area of the internal membranes and cristae decreases by 1.54 times. In such cells, the endoplasmic reticulum is represented only by membranes of the smooth type. The structure of the mitochondria and endoplasmic reticulum in the seedling cells of TAH 829, which is more like Agropyron in winterhardiness, is similar to that of Agropyron cells; in hybrid 822 (more like wheat containing the D genome), changes arise resembling those observed in wheat. The existence of different types of mitochondria in seedling cells of TAH is especially distinct at low temperatures.The mitochondria of the cereals studied differ in biochemical activity after low temperature treatment (0 ° and — 4 °C). Phosphorylative and oxidative activity of mitochondria of the winterhardy forms (Agropyron glaucum, TAH 829) decreases just after the beginning of low temperature treatment. At the same time, the morphology of the mitochondria undergoes reversible changes. The mitochondria of cold-susceptible forms of wintering plants (Triticum aestivum, TAH 822) do not conform to this pattern. Under long-term low temperature treatment they display irreversibly damaged mitochondria. It is suggested that the winterhardy forms have high adaptability connected with a rapid protective response of the cell mitochondria and endoplasmic reticulum. This adaptability is regulated by nuclear genes: TAH have different mitochondria in the coleoptile cells; if genome X of Agropyron is present, which TAH derives from the male parent, the related mitochondria become more resistant to low temperature treatment.     

Impact of ivermectin on the ultrastructure of the testis of <Emphasis Type="Italic">Argas (Persicargas) persicus</Emphasis> (Ixodoidea: Argasidae)

Mated male Argas persicus were dissected 1 and 2 weeks after feeding on untreated and ivermectin (IVM)-treated pigeons. One week after feeding, testes of untreated ticks were filled with rounded spermatids with subplasmalemmal vesicles and cytoplasmic organelles, but lacking in treated ticks. Two weeks after feeding, testes were crowded with elongated spermatozoa supported by double-walled cisternal tubes. The tubes consisted of two opposite walls, each with outer-fringed processes and inner elongated cisternae. Both were supported with electron dense striated plates in the middle of the spermatozoon. Internally, the cisternal tubes contained mitochondria and vacuoles. The nuclei were elongated dense masses between the tubes and the cell membranes. Subcutaneous inoculation of IVM at the dose 400 μg/kg pigeon resulted in extensive alterations in the testis of A. persicus. IVM prevented the development of new spermatids. There was a break down of cell membranes and cytoplasmic organelles of spermatozoa. Multivesicular bodies and numerous vacuoles were noticed in their cytoplasm. Double membranes of elongated cisternae and striation of electron dense plates became indistinct. IVM caused granulation and vacuolization of the nucleus as well as injury of mitochondrial cristae. The results suggest that IVM may bind to the neurotransmitter or the hormone involved in the process of sperm development or may be toxic to the germinal cells of A. persicus testis.     

The microtubule-dependent formation of a tubulovesicular network with characteristics of the ER from cultured cell extracts

The formation of a dynamic tubulovesicular membrane network that resembles the endoplasmic reticulum (ER) has been observed in extracts of cultured chick embryo fibroblasts (CEF cells) using video-enhanced differential interference contrast microscopy. Initially, membranes in the CEF extracts appeared amorphous and aggregated, but with time, membrane tubules moved out along stationary microtubules. The membrane tubules formed new branches on intersecting microtubules and fused with other branches to form a network of interconnected polygons. The tubulovesicular network was solubilized by detergent and took on a beaded morphology in a hypotonic buffer. Formation of the tubulovesicular network required ATP and microtubules. The network did not contain elements of the plasma membrane, Golgi apparatus, or mitochondria but could be labeled with ER markers. We suggest that the tubulovesicular network contains components from the ER and is formed by membrane associated motors moving upon microtubules in a process we call microtubule-dependent tethering.     

OBSERVATIONS ON THE FINE STRUCTURE OF LUTEIN CELLS : II. The Effects of Hypophysectomy and Mammotrophic Hormone in the Rat

Corpus luteum formation was induced in 26-day-old rats which were subsequently hypophysectomized and injected with mammotrophic hormone (MH, LTH). Sections of corpora lutea from these animals were examined with the electron microscope and compared with similarly prepared (Caulfield's fixed, Araldite embedded) corpora from normal pregnancy and from controls, the latter consisting of corpora prior to hypophysectomy and corpora from uninjected rats 7 to 14 days after hypophysectomy. Lutein cells from corpora lutea of injected animals and of normal pregnancy are characterized by abundant, tortuous, tubular agranular endoplasmic reticulum and by mitochondria, many of which are disc-shaped with dense matrices and both villiform and lamelliform cristae. The endoplasmic reticulum is most abundant in lutein cells from pregnant animals, in which cells it is in the form of thin, highly tortuous tubules. The form of the lipid droplets seen in cells of stimulated animals varies greatly. Marginal foldings of the lutein cells on the perivascular space were found in all instances. Lutein cells from hypophysectomized animals have a less highly developed agranular endoplasmic reticulum. The mitochondria have irregular outlines and a relatively lucid matrix. The lipid droplets in these cells show less tendency to be extracted, but are not so large or abundant as in the cells of onset controls. Granules believed to contain lipid pigments are common in the lutein cells of these control animals. It is suggested that lutein cells from corpora lutea which are actively secreting progesterone may be readily distinguished from lutein cells from non-active corpora by means of the multiple characteristics enumerated. It is further suggested that mammotrophic hormone has a general effect on the metabolism of lutein cells rather than solely affecting a specific organelle, the abundance or composition of which may be the limiting factor in the production of progesterone.     

Ultrastructure of the testicular gland of Blennius pavo (Pisces,Teleostei)

Summary The testicular gland of Blennius pavo Risso, 1810 is an accessory sex organ situated ventrally, adjacent to the testis. Sperm have to cross it to reach the vas deferens. Changes in the fine structure of the gland were monitored monthly over a period of 1 year. The annual cycle is closely correlated to the reproductive cycle. Maximum synthetic activity and cell size are reached during late prespawning and early spawning. At that time the number of lipid vacuoles increases markedly. Vesicles of smooth endoplasmic reticulum ER, numerous Golgi cisternae and tubulovesicular mitochondria which are characteristics of steroid producing cells can be observed. Secretory vesicles are synthesized in the apical region of the cells and then released into the ducts of the gland. The content of lipids is maintained until the resting period. The supranuclear region of the cells contains accumulations of lamellar bodies that probably derive from lysosomal vacuoles. Fine structural characteristics suggesting the function of the testicular gland are discussed.     

Spatial associations between actin filaments, endoplasmic reticula, mitochondria and fungal hyphae in symbiotic cells of orchid protocorms

The relationships between endoplasmic reticula (ER), mitochondria, and actin filaments (Afs) were observed in uncolonized and colonized cells of symbiotic protocorms ofSpiranthes sinensis (Orchidaceae) germinated in the presence of the fungus,Ceratobasidium cornigerum. Mitochondria and ER were observed by transmission electron microscopy, and with the fluorescent probe DiOC₆ (3) (3,3′-dihexyloxacarbocyanine) combined with confocal laser scanning microscopy (CLSM). An indirect immunofluorescence method using CLSM and an indirect, pre-embedding immunogold method at the ultrastructural level were used for observation of Afs. In uncolonized cells, cortical ER showed a polygonal pattern and ER formed a network throughout the cytoplasm. In the cortex, a smooth face of ER contacted the plasma membrane. Mitochondria were associated with ER. Afs were in close proximity to ER, mitochondria and amyloplasts. Colonized cells retained cortical ER, and a smooth face of ER was also closely associated with the perifungal membrane. ER and mitochondria were present in the cytoplasmic channels bridging between the central peloton and the peripheral cytoplasm. This distribution of ER and mitochondria during fungal colonization and senescence coincided with that of Afs. The changes in the arrays of Afs accompanying symbiotic fungal colonization and senescence occurred concomitantly with the changes in ER.     

Structural changes in the granulosa lutein cells of pregnant cows between 60 and 245 days.

The structural changes in the granulosa lutein cells in the pregnant cows between 60 and 245 days, were observed. The polyhedral or pump cells has an acidophilic cytoplasm around the spherical nucleus. The glycogen granules increased in number up to 230 days of pregnancy. The lipid globules increased in size and amount during advanced pregnancy. The mitochondria showed a wide range of variations in shape and size. The matrix of many mitochondria contained dense inclusions which replaced the entire matrix in late pregnancy. The endoplasmic reticulum was chiefly of smooth type but a few stacks of the rough variety could be seen in the early days of pregnancy. Sometimes, whorls of smooth-surfaced endoplasmic reticulum enclosing mitochondria were seen. The Golgi complex was fully developed in the granulosa cells of all cases studied. The dense granules and lipid globules increased in size and number in the older corpora lutea. The cell surface showed numerous infolding of the plasma membrane.     

Serum and urinary hormones during pregnancy and the peri- and postpartum period in an Asian elephant (Elephas,maximus)

Blood and urine samples were collected weekly from an Asian elephant (Elephas maximus) for 10 months before conception, throughout pregnancy, and for 10 months after parturition. Additional daily samples were collected for 41 days before through 10 days after parturition to define endocrine events during the peripartum period. During gestation, serum progesterone concentrations increased gradually and, after ～13 weeks, were higher (P < 0.05) than those observed during the nonpregnant luteal phase. Concentrations peaked at ～12 months of gestation, gradually declined during the last month, and then decreased sharply to nondetectable levels 2 days before parturition. A 12 week lactational anestrus was observed before cyclicity resumed. The urinary profile of progestagen excretion paralleled that of circulating progesterone (r = 0.79; P < 0.05); however, radioimmunoassay of HPLC-separated fractions of urinary eluates indicated that this immunoactivity was not associated with native progesterone. After remaining basal through the first 16 weeks of gestation, serum prolactin concentrations increased to 100-fold about midterm and remained elevated until after parturition. Neither serum nor urinary cortisol concentrations were altered during pregnancy, but both increased markedly the day after parturition and remained elevated above prepartum levels for several weeks thereafter. These data indicate that analysis of serum prolactin can confirm pregnancy in the Asian elephant after ～4 months of gestation and that daily monitoring of serum or urinary progestagens is useful for predicting parturition. © 1995 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

The metabolism of oxytocin during lactation in the rabbit

1. It has been suggested that changes in the concentration of hypothalamic enzymes inactivating oxytocin might be taken as an index of hormone production (Hooper, 1966). The present work describes the changes in enzyme concentration shortly after parturition and during lactation. 2. Two groups of animals were used; one consisted of lactating animals from which litters had been removed shortly after parturition. 3. Two fractions obtained from homogenized hypothalamus contained enzyme activity. In animals which had been suckled for 3 days the enzyme activity in the supernatant fraction was three times as great as that observed during pregnancy. Between the third and fifth days the activity reverted to pregnancy levels, and remained fairly constant for as long as the animals were suckled. 4. In animals whose litters were removed shortly after birth, the enzyme activity reverted to pregnancy levels by about the third day post partum, and by the sixth day non-pregnancy levels were reached. 5. The enzymes of a particulate fraction behaved somewhat differently; 6 hr. after parturition the enzyme activity was similar to that found in pregnant animals and there was no detectable activity by the tenth day in suckled animals. In non-suckled animals the enzyme activity decreased more rapidly, and non-detectable levels were reached by the fourth day post partum.