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Dogs go through prenatal development before they are born, just like all animals do. The germinal stage, the embryonic stage, and the fetal stage are the three phases that make up this development. The first stage of prenatal growth in dogs is known as the germinal stage, which starts at fertilization and lasts for about two weeks.
In mammals, the term refers chiefly to the early stages of prenatal development, whereas the terms fetus and fetal development describe later stages. [2] [4] The main stages of animal embryonic development are as follows: The zygote undergoes a series of cell divisions (called cleavage) to form a structure called a morula.
Gestational age: 8 weeks and 0 days until 8 weeks and 6 days old. 57–63 days from last menstruation. Embryonic age: Week nr 7. 6 weeks old. 43–49 days from fertilization. The embryo measures 18 mm (3 ⁄ 4 in) in length. Fetal heart tone (the sound of the heart beat) can be heard using doppler. Nipples and hair follicles begin to form.
Another factor is due to the shortage of food stocks during winter as the insects are being driven away and as the result, bat hibernate in pregnant condition. [24] In pinnipeds, the purpose of delayed implantation is in order to increase survival chance of the young animals as the mother ensure that the neonates are born at an optimal season. [25]
In human pregnancy, prenatal development is also called antenatal development. The development of the human embryo follows fertilization , and continues as fetal development . By the end of the tenth week of gestational age , the embryo has acquired its basic form and is referred to as a fetus .
In domestic dogs, sexual maturity occurs between the ages of 6 and 12 months for both males and females, although this can be delayed until up to two years of age for some large breeds. [2] Pregnancy is possible as soon as the first estrus cycle, but breeding is not recommended prior to the second cycle. [3]
Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 36 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus.
The book proceeds along two "tracks": one series of photographs and accompanying text depict the development of the fetus from conception through to birth; the other shows a woman and her partner as her pregnancy progresses. Early images show sperm proceeding toward an ovum; cell division, implantation, and the development of the embryo are ...