Changes in milk protein composition during acute involution at different phases of tammar wallaby (Macropus eugenii) lactation

This study exploited the unusual lactation cycle of the tammar wallaby (Macropus eugenii) to characterise milk composition during acute involution, a time when the mammary gland is subjected to increased risk of infection. In early-lactation, tammar milk contains elevated levels of complex oligosaccharides and low protein and lipid content. Later in lactation, protein and lipid concentrations increase significantly, whereas carbohydrate content is reduced dramatically and changes to monosaccharides. Following initiation of involution at early-lactation, the carbohydrate concentration greatly decreased, while lipid and protein concentrations were elevated, suggesting that complex oligosaccharides are the major osmole in milk at this time. In contrast, involution at late lactation, when carbohydrate concentration was very low, led to an increase in the lipid concentration, but the concentration of protein was not significantly altered. This indicates that protein synthesis during acute involution at late lactation in the tammar may be down-regulated much more rapidly than during early-lactation. Analysis of milk at day 3 after the onset of involution at early-lactation identified a number of potential antimicrobials secreted at high concentrations, including lysozyme, dermcidin, polymeric immunoglobulin receptor and fragments of beta-lactoglobulin. These proteins may protect the mammary gland by minimising the risk of potential infection during involution.     

Ultrasonographic evaluation of uterine involution and postpartum follicular dynamics in French jennies (Equus asinus)

Uterine involution and follicular dynamics during postpartum period were studied ultrasonographically in French jennies. For the study of uterine involution in postpartum jennies (n = 6, Group S), sonographic measurements of different parts of the uterus and endometrium were made at three-day interval, starting from the day of foaling and continued up to 33 days postpartum. Uterine dimensions were also recorded in non-pregnant jennies (n = 3, Group C) throughout a cycle and compared with the dimensions of Group S jennies observed on the day of complete involution. Follicular dynamics of first and second postpartum ovulatory cycles were studied and compared with that of the single estrous cycle of Group C jennies. Jugular venous blood samples of Group S jennies were collected at weekly intervals for 49 days, commencing at the appearance of first preovulatory follicle, to support the sonographic findings. The average involution period was 22.5 +/- 1.7 days. However, it was significantly delayed (P < 0.05) in jennies which came into first postpartum ovulatory heat within Day 9 than those who came later (25.0 +/- 1.0 versus 20.0 +/- 1.0). The endometrial layer was not discernible beyond Day 15 postpartum and thus was found to be unreliable index of uterine involution. The follicular growth rate (mm per day) and diameter (mm) of preovulatory follicle in postpartum jennies were similar to that in normal cycling jennies (P > 0.05). The first and second ovulations occurred at 14.6 +/- 0.8 and 39.0 +/- 0.8 days postpartum in Group S jennies. All the corpora lutea, either echogenic or centrally non-echogenic were functionally similar and had similar life span (P > 0.05). In conclusion, the postpartum reproductive events related to uterine involution and ovarian cyclicity apparently resemble that of mares.     

Post-partum release of prostaglandin F(2alpha) and uterine involution in the cow

Peripheral plasma levels of the main blood plasma metabolite of PGF(2alpha) (15-keto-13,14-dihydro-PGF(2alpha)) and progesterone were investigated during the immediate, post-partum period in 59 normally calving cows. Uterine involution was monitored by weekly rectal palpations. The levels of the prostaglandin metabolite were high at parturition and remained thereafter elevated for periods varying up to 7-23 days. Uterine involution was completed during periods ranging from 16-53 days. According to the clinical findings, the animals were divided into three groups. Group A comprises 46 animals which had an uncomplicated, puerperal period. A significant (p<0.001) correlation between the duration of elevated prostaglandin levels and the time for completed uterine involution (Y=29.6 - 1.3 (X - 13.5)) was found for these animals. Group B animals (n=8) had periods of varying length with uterine discharge during the first 30 days post-partum. When compared to group A animals, the animals in group B had comparatively longer periods of prostaglandin release and also longer periods for completion of uterine involution. Group C animals (n=5) at times had palpable, thin-walled, cystlike structures in the ovaries during the first 30 days post-partum. In this group of animals, the periods of high prostaglandin levels, as well as for the completion of uterine involution, were similar to those for the animals in group A. Progesterone levels remained low during the immediate post-partum period and in no case were elevated levels found until the prostaglandin release had ceased.     

Mechanism of thymic involution (analysis of intrinsic and extrinsic aspects)

The mechanisms of thymic involution with age are analyzed in terms of both intrinsic and extrinsic aspects. The intrinsic factors include: decrease in the number of thymocyte-precursors (pro-T cells) in the bone marrow, in emigration of pro-T cells into the thymus, in proliferation of thymic lymphocytes and decrease in extrathymic factors promoting proliferation of thymic lymphocytes. The extrinsic factors capable to exert modulating effects on the thymic function are humoral factors of the hypothalamic-pituitary origin. It seems much easier to manipulate the extrinsic factors by controlling neuro-endocrine stimulation, and to restore the thymic involution. This is quite encouraging, because it permits restoring the impaired immune functions of the aged people.     

Milk-protein mRNAs and poly(A) in the involuting rat mammary gland return to the levels found during late pregnancy

Analyses of the rat mammary gland show that the increase in the milk-protein mRNAs during the development of lactation and the rapid disappearance of these sequences during involution are not accompanied by similar changes in the poly(A) content. During the development of lactation the casein mRNA is initially in great excess to the whey-protein mRNA and this differential expression of the genes for the two types of milk proteins is again observed during early involution. Since the amounts of poly(A) and of both milk-protein mRNAs are also similar to the amounts found in the gland during late pregnancy, these results indicate that during early involution the mammary gland has reverted to the pattern of mRNA metabolism that occurs during late pregnancy.     

Effects of T-activin on the morphology of the thymus gland in experimental injury of the lower limbs in mice (anti-stress effect of T-activin)

The effect of T-activin on thymic involution under the experimental trauma of femur was studied. T-activin in a dose of 1.0 micrograms/mouse was injected into young male (CBA X C57BL)F1 mice weighing 17.5-19.0 g before (I injection) or immediately after the fracture of the femur during 3 days. Morphometric analysis of the thymus was made 1, 5, 10 and 15 days after the trauma. It was found that T-activin suppressed the involution of the thymus, induced by the trauma, during the first 5 days and accelerate the process of its regeneration. It is suggested, that T-activin displays protective anti-stress effect on the mouse thymic involution.     

Fibroblastic growth factor receptor (FGF-R) expression during uterine involution in goat.

To investigate the possible participation of fibroblastic growth factors (FGFs) in endometrial involution, 20 multiparous goats, slaughtered on days 0, 1, 4, 10, 16 and 22 postpartum (pp), were used. Samples of different parts of the previous pregnant horns were taken and processed using streptoavidin-biotin-peroxidase complex method to analyse FGF receptor (FGF-R) expression. The percentage of positive cells in luminal epithelium, superficial and deep glands and stroma was evaluated. Epithelial, glandular and stromal cells exhibited FGF-R immunoreactivity. No differences between caruncular and inter-caruncular epithelium were observed and staining was most evident in the superficial glands. The greatest degree of FGF-R expression was seen on days 10 and 16 pp, coinciding with epithelial and stromal cellular regeneration. These results suggest that caprine uterine involution is associated with variations in the expression of FGF-R.     

Postembryonale Entwicklung und Involution der Bursa Fabricii beim Haushuhn (Gallus domesticus)

Zusammenfassung Die Bursae Fabricii von Hühnern im Alter von 1 Tag bis zu 1 Jahr werden histologisch untersucht. Dabei sind nach dem histologischen Bild Postembryonal-, Ausreifungs-, Reife-, frühes und spätes Involutions- sowie Reliktstadium zu unterscheiden. Postembryonal-, Ausreifungs- und Reifestadium weichen im wesentlichen hinsichtlich Gesamtgröße, Follikelgröße und Zellzusammensetzung voneinander ab. Die Involution kann im Alter von 14 Wochen bis 5 Monaten beginnen. Während der Involution verschmelzen die Bursafalten, das Lumen verschwindet. Die Bursafollikel verlieren an der Lumenseite zunächst die Rinde, dann das Mark. Die Restfollikel lagern sich zusammen und werden nekrotisch, ein Teil bildet Zysten. Als Reliktstadien finden sich bis zum Alter von 1 Jahr fibrotische, muskel- und gefäßreiche Gebilde, die Bursafollikel, Keimzentren oder Lymphozytenhäufchen enthalten.

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Post-hatching development and involution of the bursa Fabricii in the chicken (Gallus domesticus)

Summary Bursae Fabricii were histologically examined in chickens 1 day to 1 year old. They were divided into 6 stages based on their histological appearance: the post-hatching, maturation, maturity, early involution, late involution, and residual stages. The post-hatching, maturation, and maturity stages differ with regard to bursal size, follicle size, and cellular composition. Involution may begin at 14 weeks to five months of age. During the course of involution, the bursal plicae grow together and the bursal cavity disappears. Near the luminal surface epithelium, the bursal follicles at first lose their cortex and then later their medulla. The remnant follicles join and undergo regressive and cystic changes. Residual stages are present up to 1 year of age; they are composed of fibrous connective tissue with smooth muscle and blood vessels and contain single bursal follicles, germinal centers, or lymphatic nodules.

Für technische Mitarbeit danken wir Fräulein U. Neumann und Frau A. Schick.     

Circannual changes in the expression of vascular endothelial growth factor in the testis of roe deer (Capreolus capreolus)

Adult roe deer males show seasonal cycles of testicular growth and involution. The exact timing of these cycles requires endocrine regulation and local testicular control by autocrine/paracrine factors. Recent findings suggest that the vascular endothelial growth factor (VEGF) might have effects on both vascular and germinative cells in testis. Thus, we studied the expression pattern of vascular endothelial growth factor (VEGF) in roe deer testis using quantitative RT-PCR. The strength of VEGF mRNA expression depended on season. It reached its highest level at the peak of spermatogenesis during the pre-rutting period and had its nadir at the end of the rut when involution already began. The results suggested that VEGF may directly affect the regulation of spermatogenesis but may not be involved predominantly in testicular microvasculature as initially expected.     

Effect of external factors on gonadal activity and body mass of male golden hamsters (Mesocricetus auratus)

Summary Effects of photoperiod, temperature and food and water availability on body and testicular mass of golden hamsters were investigated. Lack of water or food inhibited body growth. Short photoperiod (LD 8:16) enhanced boyd growth in males fed poor diet but it had no effect in animals on high quality diet. Cold exposure diminished body growth in animals with access to water but not in those deprived of water. It is suggested that lowered motor activity is mainly responsible for body mass gain of animals kept under the short photoperiod.All stressful factors (water deprivation, poor diet or cold) induced involution of testes. The time course of testicular involution was similar to that induced by short photoperiod. Testicular involution was, after several weeks, followed by spontaneous recrudescence. Combination of stressful external cues speeded up testicular involution. Since the testicular involution induced by water deprivation, poor diet and cold also occurred in animals kept in constant light or under long photoperiod (which are known to produce functional pinealectomy) it is concluded that the inhibitory effects of stressful external factors on testes are not mediated by the pineal.The decrease in testosterone production induced by external cues precedes changes in testicular mass. In individuals kept in the cold, testosterone production remains low, in spite of spontaneous recrudescence of the testes. No simple relationship between testosterone concentration in the blood and testicular mass was observed.The mass of the interscapular brown adipose tissue (ISBAT) changes strikingly during the hibernation cycle. Immediately after exposure to cold it decreases and stays at the low level for 40 days. Than it increases markedly and reaches maximum after 90 days, when hibernation progresses. During the hibernation season the mass of the ISBAT decreases. Constant darkness enhances the cold-induced growth of the ISBAT only at the beginning of the hibernation season.     

The bursa cloacae (Fabricii) of struthioniforms in comparison with the bursa of other birds

The late embryonic and postembryonic genesis of the bursa cloacae (Fabricii) of struthioniforms and other birds is described and discussed. The bursa of ostrich and emu is a wall organ of the caudal cloacal chamber. The bursa of rhea is, like the bursa of Gallus, a cranial appendix of the proctodeum. Lobuli bursales of struthioniforms are composed of a peripheral pars lymphoepithelialis (PLE) and a central pars lymphoreticularis (PLR). By contrast, lobuli bursales of Gallus are composed of a peripheral PLR and a central PLE. The fine structure of the bursa of struthioniforms is described. Other than in Gallus, the apical cell association of the PLE of struthioniforms shows secretory granules. This study thus far does not answer in detail the question of how the imprinting mechanism of the B-lymphocytes operates. It is assumed that they are imprinted in the PLE. Postcapillary venules in the PLR are responsible for the transport of B-lymphocytes. Hormonal bursectomies have been made to get information about the involution of the bursa of struthioniforms. In these species, involution means a gradual metaplasia while in Gallus it means a complete degeneration of the bursa.     

Diabetes (db/db) mutation-induced ovarian involution: progressive hypercytolipidemia

Ovarian atrophy and reproductive tract incompetence are recognized consequences of the progressive expression of the overt, diabetes-obesity syndrome (DOS) in C57BL/KsJ (db/db) mutant mice. The present studies evaluated the progressive changes in ovarian cytoarchitecture, endocrine expression, and reproductive tract cytolipidemic parameters that promote reproductive failure and ovarian involution during the pre-onset, initial, progressive, and chronic expression stages of the DOS. Paired littermate control (normal: +/?) and diabetic (mutant: db/db) C57BL/KsJ females were selected for analysis of ovarian parameters at 2 weeks (pre-onset expression of DOS), 4 weeks (initial DOS expression), 8 weeks (progressive DOS: hyper-glycemic/lipidemic), and 16 weeks (overt/chronic DOS expression) of age. All 4- to 16-week-old (db/db) groups were obese, hyperglycemic, and hyperinsulinemic as compared with age-matched (+/?) controls. Prior to phenotypic expression of the DOS (2 week groups), ovarian interstitial cytolipidemia characterized the perifollicular and cortical regions of db/db tissue samples relative to +/? indices, while comparable body weight, blood glucose, as well as serum insulin and ovarian steroid hormone concentrations characterized both the +/? and db/db groups. Overt DOS expression in the 4-week-old db/db groups was characterized by body obesity, systemic hyperglycemia-hyperinsulinemia, and extensive hypercytolipidemia of ovarian folliculothecal compartments, as well as enhanced tissue lipase activities. By 8 weeks of age, progressive hypercytolipidemia characterized interstitial, thecal, and follicular granulosa cell layers of db/db tissue samples concurrent with suppressed ovarian steroid hormone production, enhanced lipid sequestration, and exacerbation of systemic hyper-glycemia/insulinemia. By 16 weeks of age, the chronic-DOS was characterized by extensive ovarian follicular involution, cortical perivascular hyperlipidemic infiltration, thecal cell atrophy, and follicular granulosa lipid imbibition. These data indicate that db/db mutation-induced ovarian structural and functional involution is a direct reflection of the cellular metabolic shift towards lipogenesis, indicated by the progressive cytoarchitectural transformation into adipocyte-like entities. The cytological indications of cellular metabolic compromise, which precede the phenotypic expression of the DOS indices, suggests that correction of these abnormal shifts in ovarian endocrine and cellular metabolism may restore, delay, or prevent the further compromise of ovarian function by db/db mutation expression.     

The cycle of follicular and interstitial cells (Leydig cells) in the testis of the marbled newt, Triturus marmoratus (Caudata, Salamandridae)

Ultrastructural examination of the marbled newt (Triturus marmoratus) testis throughout the annual cycle revealed that during the period of testicular quiescence (November-February), primordial germ cells proliferate within cords of filament-rich epithelial cells that will become follicular cells (FCs). Fibroblast-like cells surround the FCs and form the lobule-boundary interstitial cells (ICs). During the period of germ cell development from primordial germ cells to round spermatids (March-June), the FCs surrounding the developing germ cells contain scanty cytoplasm with abundant rough endoplasmic reticulum and scarce filaments. With spermatid elongation (July-August), the FC size grows, its nucleus becomes irregularly outlined, and its cytoplasm displays abundant smooth endoplasmic reticulum, residual bodies, lipid droplets, and large vacuoles. After spermatozoon release by the FCs (August-September), the adjacent ICs increase their size and transform into Leydig cells with abundant smooth endoplasmic reticulum, mitochondria with tubular cristae, and lipid droplets. During the period of testicular quiescence (November-February), the Leydig cells undergo involution, eventually developing the morphological attributes of mesenchymal cells. Intermingled among these cells, cords of filament-rich cells are observed. During this period of the cycle, spermatozoon cysts supported by FCs are present. At the beginning of the germ cell proliferation period (March), these spermatozoa are released, and the adjacent ICs undergo a transformation into Leydig cells similar to those observed in August-September. Maturation and involution of ICs occur when testosterone levels are known to be rising and falling, respectively.     

In-vivo studies of mammary development in the goat using magnetic resonance imaging (MRI)

Mammary development and regression were measured in goats in vivo using magnetic resonance imaging (MRI). Measurements were made during the first and second cycles of pregnancy, lactation and involution. In primiparous goats, and exponential pattern of growth was evident during gestation and for the first 2 weeks of lactation. Parenchyma volume correlated significantly with milk yield across goats during early lactation, and across stage of lactation within goats. Milking was discontinued in Week 26 of the first lactation. Involution was characterized by an initial accumulation of fluid (over 2 days) followed by reabsorption; parenchyma volume did not decrease significantly until the 3rd week of involution, which was also the time at which these goats were mated to start their second gestation. Their udders still contained significant quantities of fluid (40-60% of the gross volume), but parenchyma volume was also greater (by 4.7-fold) than in goats beginning their first gestation. By Week 15 of gestation there was no longer a parity difference in parenchyma; the udders of first-gestation goats had grown significantly, but those of second-gestation goats had not. Conversely, between gestation Week 15 and lactation Week 2 mammary growth was significantly more rapid in the second cycle, such that the udder was larger at the start of the second lactation.     

Seasonal changes in the fine structure of the accessory sex gland in the mole (Talpa europaea)

The mole has a single pair of accessory sex organs with features of both the prostate and the seminal vesicle, for which the term prostate gland is not appropriate. Seasonal changes occuring in this gland were related to four periods: a) the quiescence period, b) the maturation period, c) the active period and d) the involution period. During the quiescence period the cuboidal epithelial cells display a quasi-embryonic fine structure and are sparse in cytoplasmic organelles, but rich in glycogen and lipopigment. With the onset of sexual activity glycogen and lipopigment disappear and the rough endoplasmic reticulum as well as the Golgi apparatus begin to proliferate. The fully active gland is lined by a low epithelium with parallel stacks of rough endoplasmic reticulum, a large Golgi apparatus and several lysosomes and secretory granules. In the involution period the gland collapses and the epithelial cells are eliminated by hetero- and autophagic processes. During this period a great number of presumably endocrine cells were observed. The results were compared with findings in experimental studies and those on postnatal development of accessory sex glands in laboratory animals.     

The settlement and metamorphosis of the marine bryozoan Bowerbankia gracilis (Ctenostomata: Vesicularioidea)

Summary The settlement and metamorphosis of the marine bryozoan Bowerbankia gracilis has been examined by light and electron microscopy. The period of rapid morphogenesis consists of the following sequence of morphogenetic movements: 1) eversion of the internal sac, 2) retraction of the apical disc, 3) coronal involution and exposure of the pallial epithelium, and 4) closure of the internal coronal cavity. The eversion of the internal sac at the onset of metamorphosis coincides with a sudden reversal of the direction of beat of the coronal cilia. The reversed beating of the coronal cilia wafts the adhesive secreted by the internal sac over the metamorphosing larva, forming the pellicle. The internal sac is subsequently internalized and histolyzed with the corona and the other transitory larval tissues, and the extensive pallial epithelium forms the epidermis of the ancestrular body wall (cystid). Type I mesenchyme cells form an incomplete somatic mesothelium beneath the differentiating cystid epidermis, and Type II mesenchyme cells become mobile phagocytes. The main body cavity develops by the histolytic enlargement of the internal cavity formed during coronal involution. The apical disc degenerates and the polypide develops from rudiments in the oral hemisphere of the larva. The distinctive larval morphology and metamorphosis of vesicularioid ctenostomes are compared with other bryozoans, and possible evolutionary trends are considered.     

The lateral scent organs of Arvicola terrestris (Rodentia: Microtinae)

The lateral scent organs of Arvicola terrestris (L.) are basically similar in construction to those of A. scherman (Shaw), and differ in that they do not express long cylinders of secretion at the end of the breeding season, and that frequent epidermal vesicles are observed. During the year the organ of the male undergoes a cycle of activity with a peak in secretory activity shortly following the peak in the cycle of testis weight. Bilateral castration causes a marked involution of the organ in the male, which can be reconstituted by the administration of exogenous testosterone.     

Post partum ovarian activity and uterine involution in the suckled swamp buffalo (Bubalus bubalis)

Ovarian activity and uterine involution were monitored by rectal palpation, oestrus detection and plasma progesterone analysis from 3 to 4 days to approximately 150 days post partum in 38 suckled swamp buffaloes (Bubalus bubalis). The intervals from parturition to regression of the corpus luteum (CL) of pregnancy and involution of the uterus were 10 and 28 ± 6 (S.D.) days respectively. First detected oestrus and first elevation of plasma progesterone (> 0.7 ng/ml) occurred at 88 ± 26 and 96 ± 22 days in 8 and 12 buffaloes respectively. During the first 150 days post partum, 26 of 38 suckling buffaloes (68%) were acyclic (anoestrus) and of 12 animals (32%) exhibiting ovarian cycles, 4 were not detected in oestrus. The tentative diagnosis, based on rectal palpation, that CL were present between days 30 and 90 after parturition (without concurrent luteal levels of progesterone in plasma) suggests that confirmation should be by laparoscopy. It is concluded that a delay in the resumption of ovarian cyclicity post partum represents an important factor contributing to the prolonged calving to conception interval in the suckled swamp buffalo.