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Basic medicine: physiology
Published in Roy Palmer, Diana Wetherill, Medicine for Lawyers, 2020
The gonads comprise the ovaries in the female and the testes in the male. Each gonad has a dual function: to produce germ cells, i.e. ova and spermatozoa, and to secrete sex hormones. Pituitary hormones (gonadotropins) cause enlargement of the ovary and testis during childhood, and the resultant release of gonadal hormones brings about the changes of puberty, including the growth spurt and the secondary sexual characteristics of females and males. Oestrogens and progesterone secreted by the ovary cause girls to start their monthly cycle of ovulation and menstruation, while testicular androgens stimulate the production of fertile sperm and seminal fluid. If sexual intercourse takes place during the period following ovulation, when an ovum is shed from the ovary and passes down the female genital tract, then conception may take place as the sperm penetrates the ovum. The developing embryo implants into the wall of the uterus, leading to the formation of the placenta, and placental hormones then sustain the pregnancy. At birth, which occurs around 270 days later, pituitary oxytocin governs the onset of uterine contractions. The breasts have enlarged during pregnancy under the combined actions of oestrogen, progesterone and the pituitary hormone prolactin. After birth lactation is controlled by prolactin combined with oxytocin secreted as a reflex response to suckling by the infant.
The female reproductive system
Published in Peter Kopelman, Dame Jane Dacre, Handbook of Clinical Skills, 2019
Peter Kopelman, Dame Jane Dacre
The ovaries develop from primitive gonads that are common to genetically male or female embryos. Testes are formed in the presence of an XY chromosome; otherwise ovaries develop. The fallopian tubes, uterus, cervix and upper vagina develop by fusion of the dual mesonephric systems. The lower vagina is developed from an invagination of the cloacal pit. When the process of fusion is not complete, two uteruses, two cervixes and a double vagina may be found.
Classification of Toxins in Humans
Published in Frank A. Barile, Barile’s Clinical Toxicology, 2019
In the last 50 years, the effects of environmental and occupational exposure to industrial chemicals have posed alarming risks to human health and safety. Like other endocrine organs, the male and female gonads act to maintain the reproductive integrity of the species. Thus, chemicals and drugs currently identified as environmental estrogens, whether or not they are structurally similar to the hormone, have the potential for endocrine disruption—that is, the ability of chemicals, drugs, and metals to alter steroidogenesis. Although the etiology of their adverse effects is unclear, their mechanisms influence maternal and paternal dynamics. Tables 4.10 and 4.11 outline several classes of drugs and chemicals (endocrine disruptors) that alter male and female reproductive systems, respectively. Their target mechanisms and possible adverse effects are noted.
From diagnosis to treatment of androgen-secreting ovarian tumors: a practical approach
Published in Gynecological Endocrinology, 2022
Patrycja Rojewska, Blazej Meczekalski, Grzegorz Bala, Stefano Luisi, Agnieszka Podfigurna
Androgen-secreting ovarian tumors constitute approximately 1% of all primary ovarian neoplasms. Most of these, arise from the stroma or sex cord of female gonads. Sex cord-stromal tumors (SCSTs) may produce estrogens, androgens, progesterone, and corticoids. Granulosa Cell Tumors are most common type of SCST accounting for about 70% of all cases, they are also the most frequent tumor causing hyperestrogenism [8]. Androgen-secreting tumors are less common than those producing estrogens but may occur in females of all ages. The incidence of various tumor histopathology is age dependent. Among women of reproductive age, Sertoli-Leydig Cell Tumors are the most common and account for approximately 0.5% of all primary ovarian neoplasms [9]. Pure Leydig Cell Tumors have a higher incidence in postmenopausal patients presenting with hyperandrogenism but overall account for 0.1% of all ovarian neoplasms [10]. Beyond SCSTs, a small number of other neoplasms have been found to secrete androgens, notably metastases (mostly of gastric origin), primary mucinous cystic tumors, teratomas, carcinoids, and Brenner tumors.
The Role of testosterone treatment in patients with metabolic disorders
Published in Expert Review of Clinical Pharmacology, 2021
Giovanni Corona, Giulia Rastrelli, Linda Vignozzi, Arcangelo Barbonetti, Alessandra Sforza, Edoardo Mannucci, Mario Maggi
The testis, the male gonad, is characterized by the production of gametes [spermatozoa] and hormones, from the tubular and interstitial compartments, respectively. Two pituitary hormones mainly control testicular activity: follicular stimulating hormone [FSH] and luteinizing hormone [LH]. The main hormones released by the testis are androgens, and, in particular, testosterone [T], which circulates only in a minor fraction as unbound to some proteins, including albumin and sex hormone-binding globulin [SHBG]. SHBG binds T with high affinity, most probably preventing biological action. In fact, according to the free hormone hypothesis, only unbound [free] T [FT] is able to bind with the androgen receptor [AR]. T concentrations show wide fluctuations over an entire lifespan, with elevated levels in the first postnatal period [mini-puberty] that decline thereafter before surging again during puberty. Several population-based studies have documented that in adult men T levels show a progressive decline as a function of age [1,2]. However, the apparent age-associated decline in serum T is attributable to a range of chronic conditions, which are more frequent with increasing age, including obesity and metabolic derangements. In fact, T levels can remain within the normal range in older healthy men [2]. Obesity-associated reduction of SHBG could partially explain the apparent decline in total T observed in aged subjects [2].
Effects of 1.5-GHz high-power microwave exposure on the reproductive systems of male mice
Published in Electromagnetic Biology and Medicine, 2021
Guofu Dong, Hongmei Zhou, Yan Gao, Xuelong Zhao, Qi Liu, Zhihui Li, Xi Zhao, Jiye Yin, Changzhen Wang
Testosterone is mainly secreted by Leydig cells, a small amount of which comes from the adrenal cortex. It is the most active hormone in androgens. Its main physiological function is to maintain normal gonadal function. In terms of detection results, there was no significant difference between the groups at different times after exposure. It should be noted that the values for the L group at three days and seven days post-exposure were high compared to the values for the other groups, but there was no significant difference between the L group and other groups. This could be because of significant individual differences in serum testosterone levels across the mice. The results showed that 1.5-GHz microwave exposure at 3, 6, and 12 W/Kg for 30 min did not significantly influence the secretion of testosterone in mice (Table 1).