Hagfish Development

  title={Hagfish Development},
  author={Aubrey Gorbman},

Current Knowledge of Hagfish Reproduction: Implications for Fisheries Management1

New evidence from recent reproductive studies that Atlantic hagfish may have a seasonal reproductive cycle is summarized, including seasonal changes in gonadotropin-releasing hormone (GnRH), gonadal steroids, estradiol and progesterone, corresponding to gonadal reproductive stages along with the putative identity of a functional corpus luteum.

Using information in taxonomists’ heads to resolve hagfish and lamprey relationships and recapitulate craniate–vertebrate phylogenetic history

This reanalysis emphasises that the debate on whether the Cyclostomata is monophyletic or paraphyletic must be resolved formally on the basis of principles and practices for phylogenetic systematic analysis including fossil data.

Development and evolution of the vertebrate primary mouth

In this paper, primary mouth formation is reviewed from a comparative point of view in order to reveal its underestimated morphogenetic diversity among, and also within, particular vertebrate clades.

The Agnathan Enteropancreatic Endocrine System: Phylogenetic and Ontogenetic Histories, Structure, and Function1

It is concluded that due to the ancient lineage and successful habitation of lampreys and hagfishes, and the importance of the EP system to their survival, that their EP systems should be a research focus well into the next century.

Thyroid and endostyle development in cyclostomes provides new insights into the evolutionary history of vertebrates

This work shows that the thyroid gland of hagfish undergoes direct development from the ventrorostral pharyngeal endoderm, where the previously described endostyle-like primordium was not found, and challenges the plesiomorphic status of the lamprey endstyle and proposes an alternative hypothesis where the lampreys endostyles could be obtained secondarily in crown lampreys.

Hagfish to Illuminate the Developmental and Evolutionary Origins of the Vertebrate Retina

This finding of eye growth late into hagfish ontogeny is unexpected given the degenerate eye phenotype and further studies dissecting retinal neurogenesis in jawless vertebrates would allow for comparison of the mechanisms of retinal development between cyclostome and gnathostome eyes and provide insight into the evolutionary origins of the vertebrate eye.

Evolution of Thyroid Enhancement of Embryogenesis and Early Survival

This parental relationship appears to be the most likely evolutionary basis for emergence of the vertebrate thyroid endocrine system, and its critically important development-promoting actions in larval and (later) fetal ontogeny.

Phylogeny and evolutionary history of the amniote egg

Except for the amnion, chorioallantois, and amniote type of eggshell, these features evolved convergently in almost all major clades of aquatic vertebrates possibly in response to selective factors such as egg predation, hostile environmental conditions for egg development, or to adjust hatching of young to favorable season.

Connection between seminiferous tubules and epididymal duct is originally induced before sex differentiation in a sex‐independent manner

In the present study, basic information such as timing, localization, and cell types involved in the connection was obtained by sequential immunohistochemistry.