The Reproductive System Images
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Conceptual Vocabulary for The Reproductive System
A spermatozoon is the haploid cell that is the male gamete. It joins an ovum to form a zygote.
An ovary is the egg-producing reproductive organ found in female organisms
The uterus or womb is the major female reproductive organ. One end, the cervix, opens into the vagina; the other is connected on both sides to the fallopian tubes.
An ovum is a haploid female reproductive cell or gamete.
Spermatogenesis is the process by which male spermatogonia develop into mature spermatozoa.
The acrosome is an organelle that develops over the anterior half of the spermatozoon's head which contains digestive enzymes including hyaluronidase and acrosin.
A gonad is an organ that makes gametes.
Testosterone is the principal male sex hormone and an anabolic steroid. It is rimarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands.
Ovarian follicles are the basic unit of female reproductive biology, roughly spherical aggregations of cells found in the ovary.
An oocyte is a female gametocyte or germ cell involved in reproduction, in other words, an immature ovum.
Luteinizing hormone is synthesized and secreted by the anterior lobe of the pituitary gland. In the female, an acute rise of LH triggers ovulation. In the male, LH stimulates Leydig cell production of testosterone.
Follicle stimulating hormone is secreted by the anterior pituitary gland to stimulate the growth of Graafian follicles in women and enhance the production of androgen-binding protein by Sertoli cells in men.
Labelled the female hormone but also present in males, estradiol is the major estrogen in humans, not only of critical importance for reproductive and sexual functioning, but also affects other organs.
Progesterone is a steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis.
The menstrual cycle is a recurring cycle of physiologic changes under endocrine control necessary for reproduction that occurs in females.
Ovulation is the process by which a mature ovarian follicle ruptures and discharges an ovum.
Menstruation is a phase of the menstrual cycle in which the endometrium is shed.
Fertilization is fusion of gametes to form a new organism of the same species.
Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates.
Oogenesis is the creation of an ovum, the female process of gametogenesis.
The corpus luteum is a temporary endocrine structure in mammals, involved in the production of the progestogens which are needed for the maintenance of a pregnancy.
The follicular phase, or proliferative phase, is the phase of the menstrual cycle during which follicles in the ovary mature to climax with ovulation.
Implantation is an event that occurs early in pregnancy in which the embryo adheres to the wall of uterus.
The luteal phase, or secretory phase, is the latter phase of the menstrual cycle, which begins with the formation of the corpus luteum and ends in either pregnancy or luteolysis.
The placenta is an ephemeral organ present during pregnancy, which develops from the same sperm and egg cells that form the fetus, and functions as a fetomaternal organ for filtration and transfer.
A spermatogonium is an intermediary male gametogonium in the production of spermatozoa.
A spermatocyte is a male gametocyte which is derived from a spermatogonium.
The term spermatid refers to the haploid male gametid that results from division of secondary spermatocytes.
Seminiferous tubules are located in the testicles, and are the specific location of meiosis, and the subsequent creation of gametes, namely spermatozoa.
An oogonium is an immature ovum. It is a female gametogonium.
Folliculogenesis is the maturation of the ovarian follicle, a densely-packed shell of somatic cells that contains an immature oocyte.
The word menopause literally means the permanent physiological, or natural, cessation of menstrual cycles.
The endometrium is the inner membrane of the uterus.
Lactation describes the secretion of milk from the mammary glands, the process of providing that milk to the young, and the period of time that a mother lactates to feed her young.
A gametid is a kind of germ cell that results from the meiosis of a gametocyte.
Found adjacent to the seminiferous tubules in the testicle, Leydig cells can secrete testosterone and are often closely related to nerves.
A granulosa cell is a somatic cell found closely associated with the developing oocyte within the ovary.
Human chorionic gonadotropin is a peptide hormone made by the embryo soon after conception and later by the placenta, preventing the disintegration of the corpus luteum and thereby maintaining progesterone levels for pregnancy.
Menarche refers to the first menstrual period, or first menstrual bleeding.
The zona pellucida is a glycoprotein membrane surrounding the plasma membrane of an oocyte.
The chorion, which surrounds the embryo and other membranes, consists of two layers: an outer layer formed by the primitive ectoderm or trophoblast, and an inner layer formed by the somatic mesoderm in contact with the amnion.
The amnion is a membranous sac which surrounds and protects the embryo.
A hyaluronidases is an enzyme released by the acrosome of the sperm cell that degrade hyaluronic acid.
The acrosome reaction is the reaction which occurs in the anterior of the sperm's head as it approaches the zona pellucida.
Capacitation is the final step in the maturation of mammalian spermatozoa and is required to render them competent to fertilize an oocyte.
The cortical reaction, also known as the zona reaction, occurs when a sperm unites with the egg's plasma membrane, altering the zona pellucida to prevent other sperm from binding to and entering the egg.
Activated by follicle-stimulating hormone, sertoli cells are 'nurse' cell of the testes, nurturing developing sperm cells within the seminiferous tubules.
Inhibin is a peptide that is an inhibitor of FSH synthesis and secretion, participating in the regulation of the menstrual cycle.
Activin is a peptide that enhances FSH synthesis and secretion and participates in the regulation of the menstrual cycle.
The epididymis is a narrow, tightly-coiled tube connecting the efferent ducts of each testicle to its vas deferens.
The vas deferens are muscular tubes surrounded by smooth muscle connecting the left and right epididymis to the ejaculatory ducts.
A bulbourethral gland, or Cowper's gland, is one of two small exocrine glands present in the reproductive system of human males. During sexual arousal each gland produces a clear, viscous secretion known as pre-ejaculate.
The prostate is a compound tubuloalveolar exocrine gland of the male mammalian reproductive system.
In a viviparous animal, the embryo develops inside the body of the mother, as opposed to outside within an egg.
Estrone is an estrogenic hormone secreted by the ovary, the least prevalent of the three estrogens, which also include estriol and estradiol.
Colostrum is a form of milk produced by the mammary glands in late pregnancy and the few days after giving birth.
Chorionic villi are tiny, finger-like structures that sprout from the chorion, in order to give a maximum area of contact with the maternal blood.
The yolk sac is the first element seen in the gestational sac during pregnancy, usually at 5 weeks gestation. It is filled with the vitelline fluid.
Acrosin is a protease released from the acrosome of spermatozoa as a consequence of the acrosome reaction
Spermatocytogenesis is the male form of gametocytogenesis which involves stem cells dividing to produce a population of cells destined to become mature sperm.
Spermatidogenesis is the creation of spermatids from secondary spermatocytes during spermatogenesis.
Spermiogenesis is the final stage of spermatogenesis which sees the maturation of spermatids into mature, motile spermatozoa.
Human placental lactogen, also called human chorionic somatomammotropin, is a polypeptide placental hormone that modifies the metabolic state of the mother during pregnancy to facilitate the energy supply of the fetus.
Trophoblasts are cells forming the outer layer of a blastocyst. They provide nutrients to the embryo and develop into a large part of the placenta.
Androgen-binding protein is a glycoprotein produced by the Sertoli cells in the testis which binds specifically to testosterone, dihydrotestosterone, and 17-beta-estradiol.
The efferent ducts are part of the testis, connecting the rete testis with the head of the epididymis.
Dehydroepiandrosterone is a steroid prohormone produced from cholesterol. It is the precursor of androstenedione, which undergoes further conversion to produce testosterone, estrone or estradiol.
Androstenedione is a steroid intermediate fromed from dehydroepiandrosterone in the biochemical pathway that produces the androgen testosterone and the estrogens estrone and estradiol.
Androsterone is a steroid hormone with weak androgenic activity, made in the liver from the metabolism of testosterone.
Dihydrotestosterone is a biologically active metabolite of the hormone testosterone, formed primarily in the prostate gland, testes, hair follicles, and adrenal glands by the enzyme 5 alpha-reductase.
The cumulus oophorus is a mass of cells of the membrana granulos projecting into the cavity of a mature Graafian follicle.
Gonadotropes are cells in the anterior pituitary which produce the gonadotropins follicle-stimulating hormone and luteinizing hormone.
Aromatase is an enzyme of the cytochrome P450 superfamily whose function is to aromatize androgens, that is, to selectively increase their aromaticity, producing estrogens.
Syncytiotrophoblasts are multinucleated cells found in the placenta of human embryos that form the outermost fetal component of the placenta and massively increase the surface area available for nutrient exchange.
The vitelline veins are veins which drain blood from the yolk sac.
Vitelline circulation refers to the system of blood flowing from the embryo to the yolk sac and back again.
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