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List of mammalian gestation durations. This is a collection of lists of mammal gestation period estimated by experts in their fields. The mammals included are only viviparous ( marsupials and placentals) as some mammals, which are monotremes (including platypuses and echidnas) lay their eggs. A marsupial has a short gestation period, typically ...
The first trimester begins with the start of gestational age as described above, that is, the beginning of week 1, or 0 weeks + 0 days of gestational age (GA). It ends at week 12 (11 weeks + 6 days of GA) [4] or end of week 14 (13 weeks + 6 days of GA).
Pregnancy (mammals) A pregnant lioness. In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once it leaves the uterus.
An ultrasound showing an embryo measured to have a crown-rump length of 1.67 cm and estimated to have a gestational age of 8 weeks and 1 day. Crown-rump length ( CRL) is the measurement of the length of human embryos and fetuses from the top of the head (crown) to the bottom of the buttocks (rump). It is typically determined from ultrasound ...
Gestation. Drawing of a fetus in utero. Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). [1] It is typical for mammals, but also occurs for some non-mammals. Mammals during pregnancy can have one or more gestations at the same time, for ...
Gestational sac. Contents in the cavity of the uterus seen at approximately 5 weeks of gestational age by obstetric ultrasonography. Artificially colored, showing gestational sac, yolk sac and embryo (measuring 3 mm as the distance between the + signs). The gestational sac is the large cavity of fluid surrounding the embryo.
Cattle. Female cattle, also referred to as "heifers" in agriculture, will gradually enter standing estrus, or "standing heat," starting at puberty between 9 and 15 months of age. The cow estrous cycle typically lasts 21 days. Standing estrus is a visual cue which signifies sexual receptivity for mounting by male cattle.
For example, if there is a gestational age based on the beginning of the last menstrual period of 9.0 weeks, and a first-trimester obstetric ultrasonography gives an estimated gestational age of 10.0 weeks (with a 2 SD variability of ±8% of the estimate, thereby giving a variability of ±0.8 weeks), the difference of 1.0 weeks between the ...