Reproductive Endocrinology Isabel Hwang Department of Physiology Faculty of Medicine University of Hong Kong Hong Kong May2007 isabelss@hkucc.hku.hk
Reproductive Endocrinology Isabel Hwang Department of Physiology Faculty of Medicine University of Hong Kong Hong Kong May2007 isabelss@hkucc.hku.hk
Begin A 3-hormone chain of command controls reproduction with the GnRH brain being the primary itary regulator. ♀田 Secretes FSH and LH FSH and LH Secrete >Gametes sex hormones① Sex hormones Reproductive tract
A 3-hormone chain of command controls reproduction with the brain being the primary regulator
Copyright The MeGraw-Hil Companies,Ine.Permission requred for reproduction or disptay TABLE 17-1 Stages in the Control of Reproductive Function 1.During the initial stage,which begins during fetal life and ends in the first year of life (infancy),GnRH,the gonadotropins,and gonadal sex hormones are secreted at relatively high levels. 2.From infancy to puberty,the secretion rates of these hormones are very low,and reproductive function is quiescent. 3.Beginning at puberty,hormonal secretion rates increase markedly,showing large cyclical variations in women during the menstrual cycle.This ushers in the period of active reproduction. 4.Finally,reproductive function diminishes later in life,largely because the gonads become less responsive to the gonadotropins.The ability to reproduce ceases entirely in women
Figure 17-2 Meiosis is the process of producing gametes(sperm and eggs)that have only one chromosome instead of a pair. This picture represents a hypothetical case for a species with 4 chromosomes 8 (2 pairs;humans have 23 pairs of chromosomes). Blue and red colors indicate the parental origin of chromosomes;note that two of the gametes formed represent new combinations 3 3 of genetic information. ①。 D①
Meiosis is the process of producing gametes (sperm and eggs) that have only one chromosome instead of a pair. This picture represents a hypothetical case for a species with 4 chromosomes (2 pairs; humans have 23 pairs of chromosomes). Blue and red colors indicate the parental origin of chromosomes; note that two of the gametes formed represent new combinations of genetic information. Figure 17-2
A representative cross-section of the seminiferous tubules in the testis is sketched here. Blood vessel Sertoli cells Sperm In response to follicle stimulating hormone and testosterone,the Sertoli cells support spermatogenesis. In response to luteinizing hormone,the Leydig cells produce steroids,including testosterone
A representative cross-section of the seminiferous tubules in the testis is sketched here. In response to follicle stimulating hormone and testosterone, the Sertoli cells support spermatogenesis. In response to luteinizing hormone, the Leydig cells produce steroids, including testosterone
The seminiferous tubules in this testis are apparent in the area that has been cut away.Spermatozoa move from the tubules into the rete testis,and then into the epididymis,first into the efferent ductules,and then into the vas deferens. Efferent ductules Epididymis Seminiferous tubule Rete testis Vas deferens Figure 17-5
Figure 17-5 The seminiferous tubules in this testis are apparent in the area that has been cut away. Spermatozoa move from the tubules into the rete testis, and then into the epididymis, first into the efferent ductules, and then into the vas deferens
Semen is composed of Vas spermatozoa and Ejaculatory Seminal deferens duct vesicle fluids from the Ureter testes,the epididymis,the Pubic bone seminal vesicles. and the bulbourethral and prostate Prostate gland Penis. glands; Bulbourethral gland enlargement of -Epididymis the latter can Urethra Testis block urine flow. Figure 17-6
Figure 17-6 Semen is composed of spermatozoa and fluids from the testes, the epididymis, the seminal vesicles, and the bulbourethral and prostate glands; enlargement of the latter can block urine flow
Chromosomes Chromatids per per cell chromosome Spermatogonia 46 Mitosis Differentiation Primary sp matocytes 46 2 1st meiotic division ondary spermatocytes 23 2nd meiotic division rmatids 23 Differentiation Spermatozoa 1 Spermatogenesis is the testicular process in adult males that generates haploid gametes capable of fertilizing ova. The overall result is that the set of 23 pairs of homologous chromosomes is reduced to a set of 23 chromosomes per sperm-the corresponding 23 pairs are present in ova
Spermatogenesis is the testicular process in adult males that generates haploid gametes capable of fertilizing ova. The overall result is that the set of 23 pairs of homologous chromosomes is reduced to a set of 23 chromosomes per sperm–the corresponding 23 pairs are present in ova
Click here to play the Spermatogenesis Flash Animation
Click here to play the Spermatogenesis Flash Animation
Figure 17-9 Sertoli cells support spermatogenesis in the seminiferous tubules in response to testosterone and FSH
Sertoli cells support spermatogenesis in the seminiferous tubules in response to testosterone and FSH. Figure 17-9