cartilaginous neurocranium
The primitive cartilagionous skeletal structure of the fetal skull that grows to envelop the rapidly growing embyonic brain. In humans, the chondrocranium begins forming at 28 days from mesenchymal condensations and is fully formed between week 7 and 9 of fetal development. While the majority of the chondrocranium is succeeded by the bony skull in most higher vertebrates, some components do persist into adulthood.[1] In Cartilagious fishes and Agnathans, the chondrocranium persist throughout life.[2] Embryologically, the chondrocranium represent the basal cranial structure, and lay the base for the formation of the endocranium in higher vertebrates[WP].