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Seminar AgendaThe Reproductive System
Questions & Answers
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The Reproductive System
3http://www.itcilo.org/
Male Reproductive System
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• 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
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The wall of a seminiferous tubule is formed by epithelial cells called Sertoli cells. Their plasma membranes adhere tightly to developing germ cellsElongated, euchromatic nuclei and prominent nucleoliaEstablish the blood-testis barrierTake up nutrients from the blood and export them to germ cellsHave an endocrine function and secrete inhibin, which
suppresses the secretionStimulate cell division and differentiation of germ cellsFacilitate 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
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Primordial germ cells are located in the basal surfaces of Sertoli cells within seminiferous tubules
Called SpermatogoniaFunction as stems cells that replenish the germ cell
population as cells are shed into the lumenA human male can produce as many as 100 million
fully differentiated sperm a dayWhen differentiate and divide by meiosis, they
move apically and are term spermatocytesSpermatocytes undergo two meiotic divisions to
haploid state and are called spermatids
Male Reproductive System: Sertoli cell and associated germ cells
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Meiosis
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2N
1N
N = number of genomes
Male Reproductive System: Spermiogenesis
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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
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Male Reproductive System: Leydig cells
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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
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Male Reproductive System
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Male Reproductive System
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Simple cuboidal epithelium of the rete testis
Male Reproductive System
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Epididymis on left Efferent ductule on right
Male Reproductive System
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Epithelium of the epididymis
Male Reproductive System
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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
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Prostrate gland showing secretory acini, urethra and ejaculatory ducts
Male Reproductive System
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Cross section of penis
Female Reproductive System
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OvariesForm in a fetus under influence of X chromosomePrimordial germ cells, called oocytes, in outermost cortical region
of ovaryPrimordial 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
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Female Reproductive System
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Female Reproductive System
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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
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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
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Female Reproductive System
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Female Reproductive System
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Questions
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