Reproduction

Lee, V. W. K.; Cumming, I. A.; de Kretser, D. M.; Findlay, J. K.; Hudson, B.; Keogh, E. J.

doi: 10.1530/jrf.0.0460001pmid: 1271330

Summary.Plasma LH, FSH and testosterone concentrations were measured by radioimmunoassays in male crossbred Merino/Corriedale sheep from birth to 45 weeks of age. FSH levels were 11 and 22 ng/ml at birth, increased to peak levels (mean value of 47 ng/ml) at 5 weeks and fluctuated between 25 and 35 ng/ml for the next 40 weeks. Similarly, LH (<0·5 ng/ml and testosterone (<38 ng/100 ml) levels were low at birth and were significantly elevated by 5 weeks of age. LH values varied between 0·9 and 3·0 ng/ml for the next 30 weeks and then a secondary rise occurred reaching levels of 2-4 ng/ml by the 41st week after birth. Concentrations of LH subsequently fell to levels observed in adult rams. Testosterone levels rose gradually between the 5th and the 25th week, and then increased rapidly to values of 270-517 ng/100 ml by the 41st week after birth, a time coincident with the peak LH levels.Histological examination of testicular biopsies demonstrated that Sertoli cell maturation occurred 17-21 weeks after birth and was followed by activation of spermatogenesis leading to the presence of spermatozoa in the seminiferous epithelium by 39-42 weeks of age.

Lee, V. W. K.; Cumming, I. A.; de Kretser, D. M.; Findlay, J. K.; Hudson, B.; Keogh, E. J.

doi: 10.1530/jrf.0.0460007pmid: 775072

Summary.The response of the pituitary-testicular axis to LH-RH infusion was investigated in rams from birth to sexual maturity. During early postnatal life ram lambs were responsive to LH-RH stimulation and heightened pituitary sensitivity was observed in rams aged 2-3 months. It is suggested that a change in sensitivity of the pituitary-testicular axis occurs at this time and perhaps represents the time of initiation of the pubertal process.

Jorge, W.; Butler, Sandra; Benirschke, K.

doi: 10.1530/jrf.0.0460013pmid: 944778

Summary.An accidental mating between a male eland and a female kudu produced an animal with primarily eland phenotypic characteristics. Despite pronounced male behaviour the animal was azoospermic. Histological examination of the testis showed complete lack of germ cells. Chromosome studies with analysis of Giemsa bands showed that the parental karyotypes differed by two reciprocal translocations and one pericentric inversion, involving chromosomes 1 and 3, 5 and 11, and 9 respectively. All other chromosomes had identical banding patterns.

Fritz, Irving B.; Rommerts, Focko G.; Louis, B. Gregory; Dorrington, Jennifer H.

doi: 10.1530/jrf.0.0460017pmid: 178864

Summary.Sertoli cell-enriched preparations from testes of 20-day-old rats were cultured in a defined medium in the presence and absence of FSH or dibutyryl cyclic AMP (dcAMP). Androgen-binding activity was assayed in the culture medium, and related to testicular androgen-binding protein (ABP). The production and secretion of ABP by the Sertoli cell-enriched preparation was increased after FSH or dcAMP treatment of the primary culture. It is concluded that ABP is produced by Sertoli cells. The possibility of involvement of other cell types in the testis in ABP production is discussed.

Kilpatrick, M. J.; Collins, W. P.; Newton, J. R.

doi: 10.1530/jrf.0.0460025pmid: 775070

Summary.A continuous flow system has been developed to study the endocrine functions of isolated organs. The procedure has been used to investigate the effect of a synthetic gonadotrophin-releasing hormone (Gn-RH) upon the anterior pituitary gland of the adult male rat. A Radiometer blood gas/pH analyser was used to monitor the pH and partial pressures of oxygen and carbon dioxide in the perfusion medium. A series of six experiments with four pituitaries per flask established that the rate of gonadotrophin release under basal conditions was 646±301 (S.D.) ng LH/ml and 404±124 (S.D.) ng FSH/ml. The duration and intensity of the response to Gn-RH was assessed by measuring the areas under the curves according to the trapezoidal rule. A significant increase in the release of FSH and LH was obtained by the administration of 250 ng Gn-RH/ml medium, and dose-response curves were produced for up to 10 μg/ml.

Brooks, D. E.

doi: 10.1530/jrf.0.0460031pmid: 1271353

Summary.The gross composition of the testicular excurrent duct system of the rat was examined and compared along the length of the duct and with samples of testis, bladder and liver. Changes in composition with age were examined by analysing tissue from animals at postnatal ages of 19, 36, 48, 60, 90 and 120 days.In adult animals, testicular tissue was characterized by having the lowest dry weight, accompanied by low levels of total protein, lipid, RNA and glycogen; DNA, phospholipids and sialic acid were at levels similar to other tissues. A high proportion of the total protein was soluble. The ductuli efferentes plus initial segment of the epididymis were characterized by high levels of total lipid. The caput epididymidis contained a low level of total protein but a high level of acid-soluble phosphorus. The cauda epididymidis had a low dry weight and low levels of total protein, soluble protein, and lipid, but high levels of acid-soluble phosphorus, DNA and sialic acid. The ductus deferens contained small amounts of RNA and DNA but had a high dry weight, high total protein, soluble protein and glycogen.Several trends were apparent with increasing age. Dry weight increased in the ductuli efferentes plus initial segment, whilst total protein decreased in the caput and cauda epididymidis. Total lipid increased in the ductuli efferentes plus initial segment and acid-soluble phosphorus and sialic acid increased in all other segments of the excurrent duct system. In all segments the content of RNA and DNA decreased as the animals matured.The concentration of calcium and magnesium in the excurrent duct system was not significantly different from those levels found in the liver.High levels of spermine and spermidine were confirmed in the prostate, and were also detected in the testis, caput epididymidis and cauda epididymidis, but at a much lower concentration.

Scaramuzzi, R. J.; Baird, D. T.

doi: 10.1530/jrf.0.0460039pmid: 944780

Summary.Six ewes were immunized against a prostaglandin F-2α-protein conjugate. Between 24 and 82 days after immunization the regular cyclic occurrence of oestrus was abolished in all six ewes. Further investigations of the immunized animals revealed that the blockade of oestrus was due to a persistence of the CL and the constantly elevated (>2 ng/ml) blood levels of progesterone. Surgical enucleation of the persistent CL was promptly followed by a fall in progesterone concentrations (<0·5 ng/ml), normal oestrus and a subsequent return to a state of constantly elevated blood progesterone levels.These results show that neutralization of the biological activity of PGF by active immunization against PGF-2α results in a failure of luteal regression and provide evidence that endogenous PGF is involved in normal luteal regression in this species.

Yanagimachi, R.; Mahi, C. A.

doi: 10.1530/jrf.0.0460049pmid: 944781

Summary.Female guinea-pigs were naturally or artificially inseminated before or after ovulation and the distribution of spermatozoa in the oviducts and the time of sperm penetration into the eggs were determined. When animals were inseminated before ovulation, the spermatozoa stayed in the distal half of the oviduct until about the time of ovulation. Only a very few spermatozoa were present in the proximal half of the oviduct at the time of ovulation, but these were sufficient to effect fertilization. When animals were inseminated after ovulation, the spermatozoa ascended the oviduct faster than when animals were inseminated before ovulation, and fertilization commenced in 4 hr. Regardless of the time of insemination, the spermatozoa participating in fertilization appeared to undergo the acrosome reaction after they reached the proximal part of the oviduct or when they were very near the eggs.

Himelstein-Braw, Ruth; Byskov, Anne Grete; Peters, Hannah; Faber, Mogens

doi: 10.1530/jrf.0.0460055pmid: 1271354

Summary.The pattern of follicular atresia was studied in nine ovaries from children between the ages 3 months and 8 years. Atretic follicles were found among follicles at all stages of development. The percentage of follicles with signs of atresia became larger as the size of the follicles increased. Only 2% of small follicles (Type 3b) showed signs of atresia, while all follicles >1 mm in diameter (Type 8) were atretic. In follicles of Type 5 and larger, four stages of atresia, which represent consecutive stages of a single atretic process, were defined. The beginning of atresia was characterized by the presence of pyknotic granulosa cells. As atresia progressed, the granulosa layer disappeared, the oocyte became necrotic, the follicle collapsed and the theca cells became hypertrophied.The oocyte can degenerate in several ways: it can be penetrated by cells, the nucleus can become pyknotic or it may complete meiotic prophase. It is suggested that the last event is only possible after the oocyte has reached its full size and has completed RNA synthesis.

Caillol, Monique; Martinet, Lise

doi: 10.1530/jrf.0.0460061pmid: 1271355

Summary.Peripheral plasma progesterone levels were studied in pregnant hares. A rise occurred at the beginning of pregnancy, followed by a plateau from Days 10 to 35, and then a drop during the days just before parturition. No significant differences were noted between progesterone levels in pregnancies initiated at the pre-partum oestrus and those from other oestrous periods.