Search results
Results From The WOW.Com Content Network
The embryo upregulates hCG, drives growth of the cell, and upregulates P4 production driving development. hCG and P4 direct changes in the mother to enable successful pregnancy (see below) via upregulation of specific hormones that act to direct both endocrinological and biological changes within the mother for successful pregnancy.
Gene duplications can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements. Common sources of gene duplications include ectopic recombination , retrotransposition event, aneuploidy , polyploidy , and replication slippage .
The breasts change during pregnancy to prepare for lactation, and more changes occur immediately after the birth. Progesterone is the hormone that influences the growth of breast tissue before the birth. Afterwards, the endocrine system shifts from producing hormones that prevent lactation to ones that trigger milk production. [3]
Menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the ...
Male development can only occur when the fetal testis secretes key hormones at a critical period in early gestation. The testes begin to secrete three hormones that influence the male internal and external genitalia: they secrete anti-Müllerian hormone (AMH), testosterone, and dihydrotestosterone (DHT). Anti-Müllerian hormone causes the ...
The ova, which are the female sex cells, are much larger than the spermatozoon and are normally formed within the ovaries of the female fetus before birth. They are mostly fixed in location within the ovary until their transit to the uterus, and contain nutrients for the later zygote and embryo .
From birth, the ovaries of the human female contain many immature, primordial follicles. These follicles each contain a similarly immature primary oocyte . At puberty , clutches of follicles begin folliculogenesis, entering a growth pattern that ends in ovulation (the process where the oocyte leaves the follicle) or in atresia (death of the ...
Evolution by gene duplication is an event by which a gene or part of a gene can have two identical copies that can not be distinguished from each other. This phenomenon is understood to be an important source of novelty in evolution, providing for an expanded repertoire of molecular activities.