The ER undergoes developmentally regulated structural remodeling during meiosis. (A) Time-lapse microscopy of cells expressing GFP-HDEL to mark the ER and Htb1-mCherry to mark chromatin (Htb1) imaged every 10 min during meiosis. Symbols mark the onset of ER cabling (yellow arrowhead), ER collapse (white arrowhead), anaphase I (⋄), and anaphase II (*). ER collapse is defined to occur at 0 min. (B) Quantification of the time of anaphase I and anaphase II relative to ER collapse. (C) Time-lapse microscopy of cells expressing GFP-HDEL (ER) and mKate-Spo20^51–91 to mark the prospore membrane (PSM). Symbols mark the onset of ER cabling (yellow arrowhead), ER collapse (white arrowhead), PSM nucleation (^), and PSM closure (#). (D) Quantification of the time of PSM nucleation and closure relative to ER collapse. (E) Cells expressing GFP-HDEL (ER), Htb1-mCherry (Htb1), and an estrogen-inducible allele of NDT80 treated with 1 µM β-estradiol (+Ndt80) or vehicle (−Ndt80) after 5 h in SPO and imaged at the indicated times following induction. (F) As in A but in cells with the endogenous promoter of CDC20 replaced with the mitosis-specific CLB2 promoter (cdc20-mn), and cells imaged every 15 min. (G) Schematic of meiosis-coupled ER remodeling with relevant cellular structures and stages of meiosis and spore formation labeled. Where applicable, dashed white line denotes cell boundary. Scale bar = 2 µm for all panels.