Equine Testis Research Articles

Two Successive Different Populations of Leydig Cells during Equine Testis Maturation

Annals of the New York Academy of SciencesVolume 513, Issue 1 p. 359-361 Two Successive Different Populations of Leydig Cells during Equine Testis Maturation G. ALMAHBOBI, G. ALMAHBOBI Laboratoire de Biochimie, UA CNRS 609, Uniuersité, 14930 Caen, FranceSearch for more papers by this authorV. PAPADOPOULOS, V. PAPADOPOULOS Laboratoire de Biochimie, UA CNRS 609, Uniuersité, 14930 Caen, FranceSearch for more papers by this authorS. CARREAU, S. CARREAU Laboratoire de Biochimie, UA CNRS 609, Uniuersité, 14930 Caen, FranceSearch for more papers by this authorP. SILBERZAHN, P. SILBERZAHN Laboratoire de Biochimie, UA CNRS 609, Uniuersité, 14930 Caen, FranceSearch for more papers by this author G. ALMAHBOBI, G. ALMAHBOBI Laboratoire de Biochimie, UA CNRS 609, Uniuersité, 14930 Caen, FranceSearch for more papers by this authorV. PAPADOPOULOS, V. PAPADOPOULOS Laboratoire de Biochimie, UA CNRS 609, Uniuersité, 14930 Caen, FranceSearch for more papers by this authorS. CARREAU, S. CARREAU Laboratoire de Biochimie, UA CNRS 609, Uniuersité, 14930 Caen, FranceSearch for more papers by this authorP. SILBERZAHN, P. SILBERZAHN Laboratoire de Biochimie, UA CNRS 609, Uniuersité, 14930 Caen, FranceSearch for more papers by this author First published: December 1987 https://doi.org/10.1111/j.1749-6632.1987.tb25040.xCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume513, Issue1Cell Biology of the Testis and EpididymisDecember 1987Pages 359-361 RelatedInformation

In equine testis microsomes, are testosterone and 19-nortestosterone aromatized by the same enzyme? [Poster 05

Testosterone and 19-nortestosterone were aromatized with about the same velocity by equine testis microsomes. Coincubations of the two substrates suggest that a single enzyme system would be responsible for their aromatization. This enzyme system had a lower affinity for 19-nortestosterone than for testosterone.

Histology of the normal and retained equine testis.

Abdominal, inguinal and scrotal testes of horses were examined grossly and by light microscopy. An average of 1.5, 2.3 and 4.6 layers of spermatogenic cells, and mean seminiferous tubule diameters of approximately 66.2, 83.6 and 146.6 micron in the abdominal, inguinal and scrotal testes, respectively, were recorded. The interstitial spaces and the number of interstitial cells (of Leydig) seemed to be increased while spermatogenesis appeared to be arrested in the retained testes. Early spermatocytes were the most mature stages of the spermatogenic cells in the retained testes. An extensive vacuolation of spermatogenic cells was evident in these testes. The changes may result due to a high temperature of the abdominal environment in concert with the altered production of androgens.

Isolation and characterization of three forms of luteinizing hormone from the pituitary gland of the horse.

Three isoforms of equine luteinizing hormone (eLH-A, eLH-B and eLH-C) have been isolated from horse pituitary glands. Separation was achieved on the basis of charge heterogeneity by ion-exchange chromatography. These charge differences were apparent after final purification, as determined by electrophoretic mobility on polyacrylamide disc gels (RF = 0.14, 0.19 and 0.26 for eLH-A, -B and -C, respectively). Apparent size differences were also noted between the isohormones by gel filtration on Sephadex G-100. Ve/Vo ratios for eLH-A, -B and -C were 1.72, 1.54 and 1.47, respectively. All 3 isoforms were found to contain an equivalent amount of hexose (9.0-9.2%). Isohormones eLH-B and eLH-C, however, possess more sialic acid than eLH-A (6.6-6.7%, vs. 4.5%). The eLH-A and eLH-B preparations contain a similar amount of hexosamine, which is slightly lower than the amount of eLH-C (8.8-9.1% vs. 11.2%). No differences were noted between the isohormones by rat Leydig cell LH bioassay, equine testis LH radioreceptor assay (RRA) or calf testis follicle-stimulating hormone (FSH) RRA. Slight, but nonsignificant, variations were noted between preparations in an eLH radioimmunoassay (RIA). Although chemical variations were detected between the eLH isoforms, no significant differences were observed in in vitro biological and immunological activities. The differences detected in sialic acid content raises the possibility that differences in in vivo clearance rates may exist.

Comparison of the properties of highly purified equine chorionic gonadotropin isolated from commercial concentrates of pregnant mare serum and endometrial cups

Commercial concentrates of equine chorionic gonadotropin derived from pregnant mare serum and equine endometrial cups were further purified by sulfoethyl-Sephadex C-50 chromatography and gel filtration on columns of Sephacryl S200. Highly purified fractions were obtained from the serum concentrate and from the endometrial cups (serum eCG and cups eCG, respectively). The two preparations were very similar chemically with respect to amino terminal amino acids (phenylalanine and serine), carbohydrate content (38–45%), and amino acid content. The cups eCG had a slightly greater average mobility than serum eCG by disc gel electrophoresis (R F = 0.37 and 0.32, respectively). Notable differences existed between the preparations in certain assay systems. The cups eCG was shown to be more potent than serum eCG by LH bioassay, LH radioimmunoassay (RIA), equine and calf testes FSH radioreceptor assays (RRA), and a RIA utilizing an antibody generated against cups eCG. In contrast, the serum and cups eCGs appeared comparably active in an equine testes LH RRA and RIA using an antibody to a serum-derived eCG. Ratios of FSH:LH activity for both preparations were consistently less than 1, but varied considerably between different assay systems. Although the preparations exhibited very little FSH activity in receptor assays utilizing equine tissues and equine gonadotropins as radioligands, considerable binding activity was measured in calf and rat testes FSH RRAs. These data confirm that variations in the nature of eCG can be reflected in chemical, biological and immunological differences. Further, the properties of eCG preparations vary depending on the source material used for isolation and the assay systems employed for evaluation.

Spermatogenesis, testicular composition and the concentration of testosterone in the equine testis as influenced by season

The influence of season on spermatogenesis, testicular composition and the concentration of testosterone in the equine testis was evaluated using testes from 45 stallions. Testes were obtained through a commercial abbatoir during September, December–January, March and July. The weights of the testes, the tunica albuginea and testicular parenchyma and the proportion of the testicular parenchyma occupied by seminiferous tubules or interstitial tissue were similar during each season. How ever, diameter of the seminiferous tubules was greater in July than during other months of the study. In addition, the concentration of testosterone within the testicular parenchyma was twice as great during July as during the fall and winter, and this period of peak testicular testosterone concentrations was associated with spermatozoal production rates, which were 65% greater than those observed in September.

Reproductive physiology of the stallion. IV. Seasonal changes in the testosterone concentration of peripheral plasma.

The normal equine breeding season begins in the spring and extends through mid-summer. It is characterized by marked increases in sperm output and seminal volume, as well as behavioural changes manifested in decreased reaction time and the number of mounts per ejaculation (Pickett & Voss, 1972). The production of androgenic steroids by the equine testis has been investigated both in vivo (Lindner, 1961) and in vitro (Savard & Goldzieher, 1960; Bedrak & Samuels, 1969; Oh & Tamaoki, 1970) but the testosterone level in peripheral plasma has not been reported (Lindner, 1961) and seasonal influences upon testicular function have received little attention. The object of this study was to establish the influence of season on the concentration of testosterone in the peripheral plasma of the stallion. Two ejaculates were collected from

Intermicrosomal distribution of aromatizing enzyme system in equine testicular tissue.

ABSTRACT The microsomal fraction (10 000–105 000 × g precipitate) of equine testes was fractionated into the smooth- and the rough-surfaced microsomal subfractions by a sucrose density-gradient centrifugation in the presence of CsCl. The validity of this fractionating procedure was confirmed by electron microscopic examination and also by chemical analysis of the RNA contents in these subfractions. The aromatizing enzyme system (19-hydroxylase and aromatase) which was concentrated in the microsomal fractions among the organellae was found to be localized in the smoothsurfaced microsomal fraction. The cytochrome P-450 which was also involved in the process of enzymatic aromatization was detected exclusively in the smooth-surfaced microsomal fraction. The distribution of the aromatizing system between the two microsomal subfractions of equine testes was discussed in comparison with that in human full term placentae.

Hormonal control of mammalian spermatogenesis.

Studies of the hormonal control of the spermatogenic process are reviewed. Most of the investigations used the techniques of ablation and replacement therapy and were performed on the rat. Results from the studies indicate that changes in the metabolism of proteins lipids and carbohydrates take place in the testes under the control of hormones. However it may be that the observed biochemical changes which occur are a reflection of the changes in cellular composition of testicular tissue rather than the result of metabolic changes within a specific cell type in response to the effect of a hormone. A hypothesis concerned with the qualitative aspects of hormonal control of spermatogenesis in the rat has been formed. It is proposed that the multiplication and growth of gonocytes prenatally and in the first few days after birth and formation of type A spermatogonia are under the control of testosterone. The formation of type A and B spermatogonia and primary spermatocytes and progression of the meiotic prophase may be influenced by growth hormone. Reduction division is under control of testosterone. The early steps of spermatid formation may be under no hormonal control or may require testosterone while the late stages of spermatid maturation require the presence of FSH.

Steroidogenesis in equine testis.

ABSTRACT When the cell-free homogenates (supernatant fluid at 800 × g) and the supernatant fluid at 10 000 × g of equine testis were incubated with 4-14C-labelled progesterone and 17α-hydroxyprogesterone, radioactive androstenedione and testosterone were isolated as the metabolites. Oestrone was also produced by the same equine testicular preparation from the above mentioned C-21 steroids, androstenedione and dehydroepiandrosterone, while 17β-oestradiol was obtained from the testosterone which had been incubated as the substrate. In addition to the androgens and the oestrogens which were obtained as the metabolites, 19-hydroxyandrostenedione, 20α-dihydroprogesterone and androst-5-ene-3β,17β-diol were identified as the metabolites by thin layer chromatography, chemical derivation procedures, and isotope dilution methods in the course of recrystallization. The testicular 19-hydroxylase and aromatizing enzyme system were found to be concentrated intracellularly in the microsomal fraction (10 000-105 000 × g precipitate), while the 20α-hydroxysteroid dehydrogenase which preferably converted progesterone into 20α-dihydroprogesterone were exclusively found in the soluble fraction or the supernatant fluid at 105 000 × g. The role and mechanism of aromatization by equine testicular preparations are discussed in relation to those of the placental microsomal aromatase.

Steroid biosynthesis by the equine testis.

Enzyme reactions in the stallion testis involved in steroid synthesis were studied to determine the factors which account for the high production of estrogens as well as androgens. In comparison with other species, the stallion testis was found to have lower 17β- (testosterone) dehydrogenase activity and very high 19-(androstenedione) hydroxylase and aromatizing systems. As a consequence, while androstenedione served as a precursor of both testosterone and estrone, a greater proportion was converted to the estrogen. The 19-hydroxylation and aromatizing activities for testosterone seemed lower than those for androstenedione. The 3β-hydroxysteroid dehydrogenase systems for 17-hydroxypregnenolone and dehydroepiandrosterone were very active, but the A6-17,20- lyase system was apparently much less active than the A4-17,20-lyase. The predominant route of biosynthesis seems, therefore, to be: pregnenolone →17-hydroxypregnenolone →17-hydroxyprogesterone →Δ4-androstenedione →19-hydroxy- ↓androstenedione→estrone te...