Please feel free to chat amongst yourselves until we begin at the top of the hour. 1

Seminar Agenda The Reproductive System Questions & Answers 2

The Reproductive System 3

Male Reproductive System 4 Gonads develop as a ventral thickening of the mesonephros tunica albuginea is tough connective tissue covering the testis bulk of tubules are seminiferous tubules where germ cells (spermatozoa) are formed Rete testis is tubules by which the spermatozoa leave the testis Tubules drain into the single, highly coiled tubule called the epididymis Diagram of the anatomy of the testis and associated ducts

Male Reproductive System: Seminiferous Tubules 5 The wall of a seminiferous tubule is formed by epithelial cells called Sertoli cells. Their plasma membranes adhere tightly to developing germ cells Elongated, euchromatic nuclei and prominent nucleolia Establish the blood-testis barrier Take up nutrients from the blood and export them to germ cells Have an endocrine function and secrete inhibin, which suppresses the secretion Stimulate cell division and differentiation of germ cells Facilitate the movement of germ cells from the basal region of the epithelium toward the apical region without disrupting the blood- testis barrier

Male Reproductive System: Germ Cells 6 Primordial germ cells are located in the basal surfaces of Sertoli cells within seminiferous tubules Called Spermatogonia Function as stems cells that replenish the germ cell population as cells are shed into the lumen A human male can produce as many as 100 million fully differentiated sperm a day When differentiate and divide by meiosis, they move apically and are term spermatocytes Spermatocytes undergo two meiotic divisions to haploid state and are called spermatids

Male Reproductive System: Sertoli cell and associated germ cells 7

Meiosis 8 2N 1N N = number of genomes

Male Reproductive System: Spermiogenesis 9 The process by which haploid spermatid undergo dramatic anatomical changes to become mature spermatozoa All of the organelles of the cell are transformed to produce a stream lined, tapering motile cell with a small nucleus Most remarkable change is the reduction in nuclear volume – 1/40 th the size of somatic cell nucleus Produce a testis-specific form of the lamin protein; which reshapes the nucleus A rigid perinuclear ring containing keratin is assembled in the cytoplasm The acrosome is formed at the anterior pole that contains a membrane-bound enzyme-rich compartment. Release of these enzymes from a spermatozoon will aid in penetrating the barriers between sperm and egg during fertilization

Male Reproductive System 10

Male Reproductive System: Leydig cells 11 Small masses of highly vascular connective tissue can be found just external to the seminferous tubules, in the interstices between tubules Specialized cells called the interstitial cells of Leydig are located in this connective tissue These cells have an endocrine function and secrete testosterone and their own specific isoform of insulin Round, euchromatic nucleus and large eosinophilic cytoplasm dominated by lipid droplets, mitochondria and smooth endoplasmic reticulum

Male Reproductive System 12

Male Reproductive System 13

Male Reproductive System 14 Simple cuboidal epithelium of the rete testis

Male Reproductive System 15 Epididymis on left Efferent ductule on right

Male Reproductive System 16 Epithelium of the epididymis

Male Reproductive System 17 Vas deferens – lumen lined with pseudostratified columnar epithelium with long microvilli plus a small amount of dense, irregular connective tissue - Thick layer of smooth muscle; a distinguishing feature of vas deferens

Male Reproductive System 18 Prostrate gland showing secretory acini, urethra and ejaculatory ducts

Male Reproductive System 19 Cross section of penis

Female Reproductive System 20 Ovaries Form in a fetus under influence of X chromosome Primordial germ cells, called oocytes, in outermost cortical region of ovary Primordial follicle = small oocyte enclosed in a single layer of simple squamous cells derived from the surrounding ovarian connective tissue (stroma) Cortical region has a layer of dense connective tissue called tunica albuginea and a layer of epithelium called the germinal epithelium At puberty, oocytes and follicles enlarge due to the expression of gonadotropins Small number develop into primary follicles

Female Reproductive System 21

Female Reproductive System 22

Female Reproductive System 23 Primary follicle zona pellucida secreted by oocyte cells outside zona pellucida round up and divide to form the cells of the granulosa layer

Female Reproductive System 24 Secondary follicle granulosa cells secrete large amounts of fluid called liquor folliculi that accumulates within a large space called an antrum As the antrum enlarges the follicle become ready for ovulation – graafian follicle

Female Reproductive System 25

Female Reproductive System 26

Female Reproductive System 27

Questions 28