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Boreoeutheria (/ b oʊ ˌ r iː oʊ j uː ˈ θ ɛr i ə /, "northern eutherians") is a magnorder of placental mammals that groups together superorders Euarchontoglires and Laurasiatheria. [ 1 ] [ 2 ] [ 5 ] The clade includes species as diverse as giraffes , pigs , zebras , rhinos , dogs , cats , rabbits , mice , squirrels , bats , whales ...
A testicle or testis (pl. testes) is the gonad in all male bilaterians, including humans, ... has external testicles. Separately from boreotherian mammals, the ...
[9] [10] [11] Moreover, this increase in scrotal storage of sperm corresponds with epididymis evolution from reptiles to mammals. The mechanism by which sperm storage in the epididymis is enhanced at lower extra-abdominal temperatures has been shown to be a consequence of the biophysics of oxygen availability and sperm oxidative respiration. [12]
Male mammals ejaculate semen through the penis into the female reproductive tract during copulation. [28] [29] Ejaculation usually occurs after only one intromission in humans, canids, and ungulates, but occurs after multiple intromissions in most mammal species. [30] [31] Copulation can induce ovulation in mammal species that do not ovulate ...
The epididymis of marsupials (metatherians) and placental mammals (eutherians) has undergone further structural differentiation compared to that observed in prototherian mammals (Figure 1). In scrotal mammals, an initial segment [ 10 ] [ 11 ] is nearly always observed, however, additional histologically distinct regions have developed between ...
Figure 1:In mammals, the quadrate and articular bones are small and part of the middle ear; the lower jaw consists only of dentary bone.. While living mammal species can be identified by the presence of milk-producing mammary glands in the females, other features are required when classifying fossils, because mammary glands and other soft-tissue features are not visible in fossils.
In most terrestrial mammals, the scrotum (pl.: scrotums or scrota; possibly from Latin scortum, meaning "hide" or "skin") [1] [2] or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin containing the external spermatic fascia, testicles, epididymides, and vasa deferentia. The ...
Male and female reproductive systems of the spotted hyena. In mammals, all intact developmentally typical males have a penis, but the clitoris in the females of the following species is sufficiently enlarged that it is usually termed a pseudo-penis: spotted hyena, [1] [2] juvenile fossa, [3] binturong, [4] lemur [5] and spider monkey.