#placenta

• abrupt separation — (Medicine, in phrases) A term borrowed from Latin used to describe a sudden detachment, instantaneous rupture, or premature separation of an organ or tissue; found exclusively in clinical contexts (e.g., abruptio placentae).
• Allantois — A sac-like, highly vascular embryonic membrane characteristic of reptiles, birds, and mammals, developing as a diverticulum of the fetal hindgut; a structural organ with vital functions in embryonic respiration, excretion, and nutrition, actively participating, in placental mammals, in the formation of the umbilical cord and placenta through its dense network of blood vessels.
• Alecithal — Relating to eggs (ovules) or animal species: lacking vitellus (yolk) or presenting an extremely reduced and insignificant amount of reserve nutritive substances in the cytoplasm. This structural type of egg is characteristic of placental mammals, where embryo nutrition is provided directly by the maternal organism through the placenta, leading to total and equal segmentation.
• Amphitherium — A genus of small fossil mammal from the Middle Jurassic period, characterized by primitive features of the mandibular dentition; from an evolutionary standpoint, it is considered a potential ancestor or an early related form of modern marsupials and placental mammals.
• Aplacental — Lacking a placenta; a mammal or organism that does not develop a placenta during the embryo's gestation period, with reproduction occurring via eggs or through fetal development inside an external marsupial pouch (e.g., monotremes and marsupials).
• Axospermous — A specialized morphological term describing plants, fruits, or ovarian structures whose seeds or ovules are attached, located, or structurally arranged directly on the central axis (axial placentation) of the carpel cavity. This vegetal geometric configuration delicately protects early-stage embryos and ensures a uniform distribution of nutritional resources during fruit maturation.
• Axospermous — Feminine form of the term axosperm, describing a plant, ovarian structure, or carpel whose ovules or seeds are inserted and structurally organized directly on the central axis of the cavity. This anatomical arrangement, known as axial placentation, is specific to many angiosperm families, providing delicate protection and a symmetrical distribution of nutrients during fruit development and maturation.